Pasture fertilization in the Everglades area as related to forage growth and animal health

Material Information

Pasture fertilization in the Everglades area as related to forage growth and animal health
Series Title:
Everglades Station Mimeo Report
Kretschmer, Albert E ( Albert Emil ), 1925-
Everglades Experiment Station
Place of Publication:
Belle Glade Fla
Everglades Experiment Station
Publication Date:
Physical Description:
9 leaves : ; 29 cm.


Subjects / Keywords:
Pastures -- Fertilizers -- Florida ( lcsh )
Forage plants -- Fertilizers -- Florida ( lcsh )
Animal nutrition -- Florida ( lcsh )
Grasses ( jstor )
Forage ( jstor )
Pastures ( jstor )
non-fiction ( marcgt )


General Note:
"January 18, 1955."
Statement of Responsibility:
Albert E. Kretschmer, Jr.

Record Information

Source Institution:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
65517851 ( OCLC )


This item has the following downloads:

Full Text
/06 J

FEB 3 1955



Albert E. Kretschmer, Jr,

This report presents the general problems
associated with pasture fertilization of
Everglades organic soils and South Florida
sandy soils as they affect plant growth and
animal well-being,


Belle GLade, Florida.

January 18, 1955.




Albert E. Kretschmer, Jr.-

The soils, agronomic, and husbandry research work associated
rith beef production is being carried on for the ultimate purpose of
producing more quantity and quality beef products at lower costs to
the producer. The nutrition of the forages being grazed or fed and
the nutrition of the animals are both integral parts of the program.
Additions of the proper fertilizer materials at adequate rates is one
of the major economical factors associated with a successful animal
operation. The common saying that "muck soils must be fertilized
heavily to produce healthy animals" should be changed to "muck soils
must be fertilized properly". Large additions of fertilizer materials
that fail to change either the quantity or the quality of the grass
being treated or the animal's health are uneconomical. Failing to in-
crease through fertilization the content of a particular element in a
forage to meet the animal's requirement, even though the forage's
requirement has been net, also is poor economy, if the animal's needs
cannot be met satisfactorily through the use of a supplementary mineral

Soil Testing-Organic Soils

There is a great deal of difference in taking a representative
soil sample from a homogenous field such as a prepared seedbed or
vegetable field prior to planting, and that of an old pasture that has
been grazed heavily. The distribution of potassium, phosphorus, and
trace elements in the former type of field should be relatively uni-
form. A physical description of such distribution could be depicted as
a flat table. Soil under pasture conditions presents a much more com-
plex picture since concentrated spots of phosphorus and potassium are
deposited by the animal through the feces and urine. The distribution
of these elements presents a much less homogenous picture, such as
could be described by a flat table upon which had been placed at random
various sizes of marbles. The size of the marble would depict the
relative quantity of potassium or phosphorus. Obtaining a soil sample,
representative of a pasture's nutrient status, is very difficult. The
fecal and urine spots will supply sufficient phosphorus and potassium
even though, under some conditions, the majority of the field will be
deficient. The phosphorus and potassium contents of a composite soil
sample, representing ten individual borings in such a field, might vary
1/ Assistant Soils Chemist, Everglades Experiment Station, Belle Glade,


considerably depending on how many manure and urine spots were un-
avoidably included in the sample.

Until experiments now being conducted at the Station are complete,
the following two steps should be followed for those interested in ob-
taining fertilizer recommendations based on soil samples taken from
pastures. These steps also are applicable to sandy soil samples. (1)
Take 10 individual soil samples with a soil tube in any similarly treated
pasture area and mix thoroughly before submitting the composite sample
for analysis. All obvious manure and urine spots should be avoided.
(2) Submit with the soil sample a summary of the fertilization history
for the area including quantities of trace elements added and forage
being grown. This step is of great importance since recommendations for
fertilization often times depend on the previous history, particularly
with respect to trace elements.

Fertilizer recommendations are presently made on the assumption
that grasses growing on organic soils containing as much as 4 pounds
of water soluble phosphorus and 80 pounds of 0.5 N acetic acid soluble
potassium will not respond to additional fertilization with these

Nutrient Requirements of Pastures-Organic Soils

The accompanying chart lists the elements known to be essential
for plant and animal well-being. They are placed into three classes
and the more important ones will be discussed more thoroughly.

Nitrogen (N)-- There is no doubt that N applications to Everglades or-
ganic soils, under certain environmental conditions, will benefit pasture
growth. Information to this effect was published several years ago.
Response to N might be expected when the following condition or condi-
tions exist: (1) compact surface soil, (2) high water table, (3) low
temperature and, (h) thick sod coverage.

Many times the protein contents of grasses may be sufficient for
maximum animal growth even though the grasses respond to additional N.
In these instances, however, a greater yield of grass will permit more
animals to graze a given area. St. Augustine grass sods would appear
to respond to N additions nore frequently than other grasses. An over-
all light green to greenish yellow color of a field of St. Augustine
grass or the appearance of a reddish discoloration on the older leaf
blades indicates the need for N.

Nitrogen toxicity or "nitrate poisoning" of animals is of some
concern to cattlemen on high nitrogen soils. Any disturbance or stop-
page of the plants' biochemical processes, responsible for the break-
down of the absorbed nitrates into proteins, will result in a tendency
for nitrate accumulation. The transformation of nitrates to nitrites
by the rumen bacteria and the eventual absorption by the blood stream
results in a reduced oxygen carrying capacity of the blood. Reduction
of this capacity may cause animal death by asphyxiation. Rye grass and
oat plants are the two offenders found in the Everglades area, both ab-
sorbing about equal quantities of nitrates particularly during the early


growth stages. Permanent grasses and legumes do not accumulate nitrates
sufficient for toxicity. Some of the factors favoring nitrate accumu-
lation are: (1) an oversupply of nitrogen in the soil, (2) well-aerated
soil in the root zone, (3) sufficient moisture supply, (4) low light
intensities, (5) insufficient carbohydrates in the plants, and (6) tem-
peratures low enough to retard plant growth.

The symptoms exhibited by affected animals usually are quite
uniform in character and are markedly increased in severity if the
animals are disturbed or forced'to move about. Some of them are: (1) a
rapid acceleration of the pulse, (2) general weakness, (3) staggering
gait, (4) apparent blindness in some instances, and (5) cyanosis or
blue coloration of the tongue and eyes. Nitrate poisoning and prussic
acid poisoning both manifest themselves in a similar manner with respect
to physical appearances of the affected animals. If the color of a
drop of blood taken from the animal's ear is chocolate brown excess ni-
trates are responsible; a cherry red color indicates prussic acid
poisoning. Animals may be cured from either type of poisoning if treat-
ed in time.

Results of tests and observations carried on at the Everglades
Station indicate that the use of quick tests are of little value in
predicting toxicity in forages. Besides being rather insensitive, such
tests indicate only the quantity of nitrates present when the sample was
taken. Nitrate contents may vary considerably during a short period of
time. Individual animal susceptibility, however, is the limiting factor.
How much of the forage the individual eats, and the condition of the
individual is important. An animal that is in a weakened condition as
a result of insufficient feed, not only is more susceptible to nitrate
toxicity but also will tend to gorge itself when first turned into a
lush ryegrass or oats pasture thereby ingesting more nitrates than a
well fed animal.

Phosphorus (P) and Potassium (K)-Larger quantities of these two elements
are added to Everglades organic soils than all others essential to for-
ages or animals. Additions of either or both may result in forage growth
response. There is little P or K lost through leaching in these soils.
Under grazing conditions the majority of r and K that is lost results
from the net gain of these elements in the animal's body during the time
the animal is left on the pasture. Although virgin peat soils probably
require 1 and K for maximum grass yields it is believed that a point will
be reached after years of fertilization so that annual additions may be

At times fertilization with K may be necessary for maximum grass
growth even though the animals' needs have been met. On the other hand,
there may be no grass response to additions of P necessary for animal
growth. A survey of pastures was made in the Everglades area, including
169 samples of various grasses and legumes being grazed. The average P
content of the forages was 0.30% and the values ranged from 0.08 to 0.66%.
Since 0.13/ P is considered the content below which animal deficiencies
might appear and since 0.20% is definitely adequate for animal health it
can be said that the forages in a majority of pastures in this area con-

trained sufficient P.

Visual symptoms of P deficiency of grasses or legumes have not
been observed on commercial plantings of grasses in this area but symp-
toms attributed to K deficiency of St. Augustine grass have been ob-
served in numerous pastures. They may be described as small, round, to
rather large elongate solid brown areas appearing first on the older
leaf blades. These symptoms must not be confused with the disease
Piricularia oryzae (a fungus disease), which manifests itself on the
foliage as spots- ith an ashen grey circular center surrounded by a brown
area. Average K contents of lt2 survey samples was 1.80%, the range
being from 0.29 to 53%. Symptoms of the deficiency are likely to
appear when the content in the grass is 1.0% or less.

Until further information is available an initial 500 pound
per acre application of 0-8-24 (hO Ibs. P204 and 120 lbs. K20)is recom-
mended to be disked into virgin soil. Yearly applications of 300 pounds
should be maintained for at least two years or until soil tests indi-
cate otherwise. Old vegetable land or heavily fertilized old pasture
land may need no further phosphate applications. Muriate of potash
(plus trace elements if necessary) may be applied to meet the require-
ments for K,

Copper (Cu) and 17olybdenum (o)-- At least 50 pounds of copper sulfate
per acre should be disked into virgin peat soil. Copper oxide on an
equivalent Cu basis (25 Ibs. of 50% copper oxide) is just as effective
as the sulfate form and at the present time is slightly less expensive.
It is doubtful that further Cu additions would be beneficial to forage
growth at least for several years. However, the animals may benefit
from such applications. At this time it is recommended that 15 to 20
pounds of copper sulfate or 8 to 10 pounds of copper oxide be applied
annually for at least two years following the initial application. It
is doubtful that Cu fertilization of old, heavily fertilized vegetable
land (turned into pasture) is of any additional benefit to the grass
or cattle, since it probably would not increase the Cu contents of the
forage. Spraying or dusting with about 15 pounds of copper sulfate or
8 pounds of copper oxide would effectively increase the Cu contents of
forage. The effectiveness of surface applications of Cu to the soil,
without disking, is not definitely known. However, appreciable Cu does
not seem to move down through these organic soils. One virgin peat soil
pasture was treated with an initial surface application of Cu at the
recommended rate. Months later after the summer rainy season, analyses
of the soil for total Cu showed 180, 2.h, and h.0 ppm Cu in the 0 to 1
inch, 2 to 3 inch, and 5 to 6 inch depths, respectively. Furthermore,
experimental tests being conducted on surface treated virgin peat soil
indicated no consistent increase in the Cu contents of Roselawn St.
Augustine grass as a result of 50 pound additions of copper sulfate or
25 pounds of the oxide compared to no Cu treatments. Copper contents
of the forage averaged h.5 ppm.

Sand land forages containing 5 ppm Cu or more (dry weight basis)
have been found to contain adequate Cu for cattle. The presence of small
quantities of Yo in the forage, however, increases the need for Cu to
about 10 ppm. Forages containing 3 ppm 1o should contain about 10 ppm Cu


to maintain healthy growth of cows. A survey was made of the Cu and
Mo contents of forages growing in the Everglades area. The 112 samples
included samples of the five main grasses used in the area as well as
white clover. Average C. and Yo contents were found to be 7.4 and 5.5
ppm, respectively, for samples taken in the fall, and 10.9 and 2.9 ppm,
respectively, for the spring samples. These results indicate that
animals not obtaining Cu through the mineral mixture may become deficient
in Cu during the winter rather than during the spring and summer months.

Manganese (]n), Zinc (Zn), and Boron (B)- Boron has not been proved
essential for animals and the requirements for In and Zn are so small that
the animals' needs may be met even when grazing forages deficient in these
elements. Field experiments are now being conducted to determine the
effects of Ln, Zn and B on grass yields. Forages such as corn, shallu,
etc., have been known to respond to these elements and undoubtedly there
is some need for them by pasture grasses. Available survey information
showed that the average En content of 105 grass and legume samples was
39 ppm, the range being from 5 to 97 ppm. Grasses used in this area un-
doubtedly would produce maximum yields when they contain less than 15
ppm. Results indicate that by far the majority of samples collected con-
tained sufficient Ln for plant growth.

At the present time the initial fertilization program should
include sufficient quantities of manganese sulfate, zinc sulfate, and
borax to supply about 25, 10 and 10 pounds per acre, respectively.
For two or three years thereafter, annual applications of about 15
pounds manganese sulfate and 5 pounds each of zinc sulfate and borax
per acre should be made. Pastures having been previously fertilized
with large quantities of these elements probably would not respond to
further additions.

Iron (Fe)- Iron applications are not recommended for forages growing
on Everglades organic soils. Analyses of 124 survey samples showed the
average to be 76 ppm with a range of 38 to 163 ppm. It is very im-
probable that there would be animal responses to additional Fe.

Cobalt (Co)-- Cobalt is not knovm to be essential for plants. Its
essentiality to ruminants is well known. Of 63 grass and legume survey
samples collected throughout the organic soil area, 17 contained 0.04
ppm or less while only 17 contained more than 0.07 ppm Co. Values ranged
from 0.01 ppm to 0.26 ppm Co, the average being 0.06 ppm. Cobalt con-
tents of forages less than 0.07 ppm may not supply sufficient Co for
maximum cattle growth while 0.10 ppm is adequate. Tore than 75% of the
survey samples, therefore, may be placed in the possibly deficient class.
Animals obtaining continuous additional Co through the supplementary
mineral should maintain a healthy condition even when grazing the more
deficient forages. Individual animals, particularly cows and calves
that fail to obtain sufficient supplementary Co may become deficient
in this element.

Applications of 6 ounces of 21% cobalt sulfate (costs about $1.00
per pound) to the organic soil in a mixed fertilizer was not very effec-
tive in increasing the Co contents of hubam clover, rye grass, oats,
alfalfa or white clover. On the other hand, Co applied by plane to
Roselawn St. Augustine grass, white clover and Para grass at the same
rate effectively increased the contents of forage to between 0.13 and

0.19 ppm Co. At the present time critical tests are being conducted
to determine the effects of soil applications of Co to established
Roselawn St. Augustine grass pastures. If Co is to be applied to
pastures on the Everglades organic soils it is recommended that about
6 ounces of 21% cobalt sulfate be flown on rather than applied in a
mixed fertilizer. The cost of flying this amount on (including the cost
of the Co) would be about (1.25 per acre.

Nutrient Requirements of Pastures-Sandy Soils

Fertilization of sandy soils is quite different from that of
the organic soils because of three main differences in their inherent
characteristics. Sandy soils do not have sufficient nitrogen to main-
tain rapid grass growth, they do not have the ability to prevent leach-
ing of potassium and other nutrients, and on a majority of sandy soils
in South Florida there is a need for added lime.

Calcium (Ca) and Magnesium (Mg)-- Most of the soils of the flatwoods
and grass prairie areas require the addition of a liming material, par-
ticularly if legumes are to be grown. A general rule of thumb can be
followed to help decide the quantity of lime necessary to bring the pH
up to 5.5, to 6.5 if the original pH is between about l.5 and 5.0. If
the original vegetation did not contain large quantities of hog and
scrub palmetto, one ton of a lime should be sufficient. If thick stands
of palmetto were growing in the proposed pasture, two tons of lime
should be added. At the present time it is believed that grasses,
and clovers, can maintain maximum plant growth when 0,. N acetic acid
soluble Eg is as low as 50 pounds per acre or lower. Vegetable crops
growing on these soils frequently exhibit foliar symptoms of Mg de-
ficiency. Since the price differential between dolomite and hi-calcic
limestones is small, it is suggested that at least one half of the lime
applied be of this form to insure a sufficient supply of ig. The liming
materials should be disked into the soil before planting. Animals con-
tinuously grazing unlimed sand land pastures may become deficient in Ca;
this is particularly true for cows and calves.

Potassium (K)-- Grasses absorb more K than the other essential elements
except for nitrogen. Both applications of potash without nitrogen, and
nitrogen application without sufficient potash being present in the
soil, are wasteful and uneconomical. The requirement of Pangola grass
for K is greater than that of Bahia grass. Under normal conditions soils
in the fall will contain little K (or nitrogen) since it is almost com-
pletely leached during the summer rainy season. Clovers require large
additions of potash for maximum growth and carbohydrate production. They
become deficient in this element before visual symptoms of the deficiency
are apparent. Clovers that have failed to receive a steady supply'of K
do not have the ability to produce good yields, are low in protein, and
fail to regrow rapidly after being grazed (because of a reduced carbo-
hydrate supply in the roots) even though they may survive for long periods
of time without additions of K. It is not unusual to have a field of
clover fix 100 pounds of N per acre per year.from the air.


Nitrogen (N)- The problem of N fertilization of sandy soils is so
complex and so controversial with respect to rates, methods, etc., that
its discussion will be limited. A good rule of thumb to follow, how-
ever, is that a grass will usually respond to additional N regardless
of when the last application was made, if all other essential nutrients
are present. The economical aspect of adding N also is a complex
problem, but additions of this element to grass pastures certainly has
proved economical.

Phosphorus (P)-- Phosphorus is also leached from sandy soils, but not
as rapidly as K. Generally speaking, the lower the soil pH, the more
available is the P and the more readily it is leached. There is suf-
ficient experimental evidence that proves the value of rock phosphate
in a sand land pasture program, when sufficient sulfur is also present.
At the present time, recommendations thought to be adequate for grasses
and clovers are such that about 800 pounds of superphosphate should be
applied over a period of 5 years through annual applications at a total
cost of approximately Q9.O0/A.This amount of total P also is supplied
by about 500 pounds of rock phosphate at a cost of about $3.50.

The price differential suggests the use of an initial 1000
pounds of rock phosphate disked into the soil at planting time. vith
the exception of the initial mixed fertilizer application, additional P
may not be needed for at least 5 years. In addition to the lime and
rock phosphate, for grasses, 300 to 500 pounds per acre of 6-6-6 plus
sufficient trace elements to supply 15 pounds copper sulfate or 8 pounds
copper oxide, 15 pounds manganese sulfate, 15 pounds ferrous sulfate, 10
pounds zinc surgate, and 10 pounds borax per acre also should be disked
in. Probably/~ore trace elements need be added for 3 to 5 years. To
maintain grass pastures applications of about a minimum of 50 pounds of
N and 50 pounds K 0 per acre should be made annually. Fifty pounds of
each in early falI and early spring will give much greater yields,

For White clover, in addition to the 1,000 pounds of rock phos-
phate, 200-300-Pounds per acre of 0-8-24 plus the same rates of trace
elements as applied for grasses should be disked in prior to seeding in
early fall. In early spring, about 200 pounds per acre of muriate
potash should be applied. Annual applications should include a fall
application (when clover reseeding commences) of about 150 pounds muriate
of potash per acre containing 5 to 10 pounds of borax, vith an early
spring application of 150 pounds muriate potash. The third year, enough
sulfate of potash, gypsum, or sulfur should be substituted for the muriate
form to supply about 30 to 10 pounds of sulfur per acre. Gypsum or sul-
fur may also be used to supply the necessary sulfur. If nitrogen is
used in the summer, supplying it in the form of ammonium sulfate will
preclude applications of additional sulfur.


'Nitrogen (1)
Phosphorus (1)(2)
Potassium (1)(3)
Copper (1)(2)
Manganese (1)(3)
Zinc (1)(3)
Sodium (2)
Chlorine (2)

Cobalt (2)

(1) Forages growing on Everglades organic soils may respond to
additions of these elements,

(2) Animals grazing forages growing on Everglades organic soils may
respond to additions of these elements even though the forages
may not respond.

(3) Animals grazing forages growing on Everglades organic soils most
likely will not respond to additions of these elements even though
the forages may respond,

Boron (1)