Everglades Station Mimeo Report EES67-11 May 1967
RECOMMENDATIONS ON FERTILIZATION AND VARIETIES OF PASTURES
FOR ORGANIC SOILS 1/
R. J. Allen, Jr.2/
Organic soils, especially the mucks and peats of southern Florida, present
quite different conditions for pastures than do the mineral or sandy soils.
As the name implies, they have a high organic content; 30 to 65 percent for
muck, 65 to 85 percent for peaty muck, and 85 to 95 percent for peat. Having
been formed under wet or swamp conditions, the native vegetation is primarily
sedges and other water plants which furnish little if any native range.
When drained, organic soils are subject to decomposition of the organic
material, which releases nitrogen to the soil. They are relatively low in
other elements, but they do have the ability to hold applied fertilizer nutrients
and to prevent excessive loss by leaching during heavy rains, which may occur
in sandy soils. The high soil nitrogen promotes rapid and luxuriant growth of
grasses and other plants, including weeds, throughout the growing season.
Therefore it is not possible to stagger the production peaks in different
pastures by applying fertilizer at different times, as can be done on sand soils.
Sod forming or dense growing types of grasses, rather than the bunch types,
are required on organic soil pastures to maintain a complete ground cover and
smother weed seedlings. These grasses, with the constant nitrogen stimulation,
also crowd out clovers and other legumes which on mineral soils are important
for nitrogen fixation.
It is obvious from the above differences, that recommendations for organic
soil pastures will be quite different from those for other soil types.
Based on considerable experience with peat and muck soils of the Everglades
region, the following general fertilizer recommendations are given as minimum
treatments for pasture grasses on organic soils.
Virgin Peat: Initial application, 0-8-24, with 3.0 percent CuO, 1.5 percent MnO,
1.0 percent ZnO, and 0.8 percent B 0 ,
applied at 500 pounds per acre.
Subsequent annual applications, 0-8-24, with 1.5 Cu0,1.5 MnO,
1.0 ZnO and 0.8 B205,
applied at 300 pounds per acre.
After 5 years change to 0-10-20 or treat as older peat soils.
1/ Prepared for Beef Cattle Short Course, May 4, 5, and 6, 1967, Gainesville,
2/ Assistant Agronomist, Everglades Experiment Station, Belle Glade, Florida
Muck Soils and Older Peats: 0-12-16, with 1.5 CuO, 1.5 I.nO, 1.0 ZnO, and 0.8
B205, applied at 300 pounds per acre.
Old Vegetable Land that has been heavily fertilized usually has enough residual
fertilizer for the establishment of pasture grass, and sometimes
for the first year or two of grazing. Depending on the fertility
history of the field, 200 to 300 pounds of 0-12-16 with 1.0 CuO may
be applied for the first 2 or 3 years, then treat as muck or older
Soil tests of virgin soils, or of soils which have been in vegetable
production, may occasionally indicate more specific requirements, but as a general
rule these treatments will establish good pastures on organic soils. However,
after the pastures have been intensively grazed, soil tests become much less
reliable due to possible contamination of samples from urine spots, which are
almost impossible to identify on organic soil pastures. Unless sampling is done
by experienced personnel and according to experiment station directions,* it may.
be better to base fertilizer applications on observations of the grass and
fertility history of the pasture.
These recommendations are for pastures only, where grass is utilized
directly by grazing animals. If the field is mechanically harvested for green
chop, silage, or hay, additional fertilizer must be applied.
Discussion of Fertilizer Elements:
Nitrogen is not normally recommended on organic soils since the organic
material which constitutes the greater part of these soils contains about 3
percent nitrogen. Under normal pasture conditions, continuing decomposition
and nitrification processes slowly but steadily release sufficient nitrogen to
fulfill the requirements of grasses. Under abnormal conditions, such as when
aeration is prevented by excess moisture or by compaction, or when the soil is
dry, the above processes are slowed or stopped and nitrogen becomes deficient.
During winter months cool soil temperatures may also slow the process and light
applications of nitrates may help winter annual grasses such as ryegrass or oats.
In loose textured soils or in areas harrowed to prevent plant growth for a period
of time, nitrates may build up enough to produce toxic conditions, especially
in the annual grasses. Heavy rains can leach nitrates from the soil, thereby
reducing an excess or in some cases causing a temporary shortage of nitrogen.
Phosphorus is usually present in virgin organic soils in sufficient
quantities for grass growth, but additional amounts are recommended to raise
the phosphate content of the grass for the benefit of the animal. As these soils
decompose, phosphate fixation may increase due to release of certain other
minerals. Therefore phosphate fertilization requirements increase as much as
50 percent as the soils continue in use.
a Everglades Station Mimeo Report:
EES65-18; "Sampling and Methods Used for Analysis of Soils"
EES65-22; "Why Fertilize That Pasture?"
Potassium is very low in organic soils and relatively heavy applications
are required for good grass growth. Since it does not leach appreciably from
these soils, potash may accumulate after several years so that annual applications
may be reduced by as much as one third.
Calcium and Magnesium contents are nearly always more than adequate when
the underlying material is marl rock or limestone. Organic soils over deep
sands may require large amounts of limestone, or preferably dolomite, thoroughly
worked into the soil to furnish sufficient'amounts of these elements to the forage
and the animal. On highly organic peats with very low pH the requirements may
be enough to make the operation uneconomical.
Sulphur contained in ordinary or 20 percent superphosphate is usually
adequate. If high analysis triple-superphosphate is used, it may in some cases
be advisable to include some sulphur in the fertilizer mixture.
Copper is deficient in most organic soils and for many years was a limiting
factor in the development of Everglades soils for animal production. Some
grasseswill grow without copper applications but will not maintain animal
health, while others will not even grow. Initial applications should be 50
pounds of copper sulphate or 25 pounds of copper oxide. Subsequent applications
should.be one fourth to one third of these amounts annually.
Manganese, Zinc, Boron and occasionally Iron are other minor elements
recommended. Manganese deficiency symptoms have been observed on grasses and it
is also a necessary element for animal nutrition. Zinc and boron deficiency has
not been observed on pasture grasses, but has been diagnosed on vegetable crops
in the Everglades area. Therefore these elements are included as a safety
or insurance measure. Iron is not recommended unless observation and analysis
indicates a need for it.
Since for practical purposes there is no native range on organic soils,
cattle on these soils are dependent on improved pastures planted to introduced
grasses. Those recommended are the following:
1. Roselawn St. Augustinegrass, Stenotaphrum secundatum,var. Roselawn.
2. Paragrass, Panicum purpurascens.
3. Argentine Bahiagrass, Paspalum notatum, var. Argentine.
4. Pensacola Bahiagrass, Paspalum notatum, var. Pensacola.
Others which may be used but will require more careful management are
Caribgrass, Eriochloa polystachya; Pangolagrass, Digitaria decumbens; Suwanee
or Coastal Bermuda-grass, Cynodon dactylon.
For temporary winter grazing, Ryegrass, Lolium multiflorum, has proved
to be the most reliable and satisfactory. Varieties of Oats and Rye developed
for Florida can also be used.
Even though cattle can remain on pasture throughout the year in most of
Florida, there is considerable variation in forage production, or carrying
capacity of pastures, between the winter months and the rest of the year,
especially on organic soils. These soils have a high production potential
during the warm seasons, but are usually more subject to cold and frost during
the winter months. These factors must be taken into consideration when planning
animal and pasture management practices.
Discussion of Pasture Grasses
Roselawn St. Augustinegrass is used on 80 to 90 percent of the grazing
land in the Everglades Agricultural Area. It is a runner type grass which forms
a good sod and is relatively free of weeds unless overgrazed. It is resistant
to light frost, and relatively free of diseases and insects, but under drought
conditions it can be damaged by chinch bugs. Planting is by stem cuttings or sod
pieces, usually the latter on large areas, since machines have been developed
for the purpose. The Roselawn strain or variety is a long internode, long leaf,
tall growing pasture type and should not be confused with other strains or
varieties of St. Augustinegrass which are used for turf or lawn purposes. It
does not make good pasture on mineral or sandy soils.
Paragrass is an aggressive tall growing grass which spreads by long coarse
runners which will root at each node. It makes a dense growth which effectively
shades out weeds and other grasses, but does not form a sod. It is very tolerant
of flooding, in fact, if not controlled it will grow into and clog water control
ditches. Paragrass is very susceptible to frost but will recover very quickly
from the crowns during warm periods. It is quite free of insect damage, but
tall mature grass is often severely damaged by a helminthosporium leaf disease.
Planting is done by spreading fresh cut tall grass, disking, and rolling. This
is the easiest grass to establish by this method.
Argentine Bahiagrass is a relatively aggressive sod forming grass with
coarse, compact stems which remain on the ground and root along their entire
length. Only the leaves and segd stalks grow upright. It is planted by seed,
preferably in early spring. It can be planted by sod pieces similar to St.
Augustine but it spreads much slower. It is quite free of both insects and
diseases, will stand light frost, and is the most tolerant of the grasses to
Pensacola Bahiagrass is similar in growth habits to Argentine. It has
narrower leaves and smaller seeds, and the seed heads appear earlier in the
spring. It is a little less aggressive but more frost resistant, and growth
starts earlier in the spring.
Both the Bahiagrasses have shown higher carrying capacity per acre but
lower weight gain per animal in grazing trials at the Everglades Experiment
Station. They are recommended as herd maintainance grasses rather than for
growing out young animals. Of the two, Argentine will give higher forage yields
over the year, but Pensacola will usually yield higher during the cold weather
and early spring. They should not be confused with Common Bahia which is not
Caribgrass is very similar to Paragrass in appearance and growth habits,
and it is difficult to distinguish between the two. The principal identifying
characteristic is the appearance of seed heads in September, 6 to 8 weeks
before Paragrass. In station grazing trials it was a little slower in
recovering from frost.
Pangolagrass is probably used on more pasture acreage in peninsular
Floriia than any other grass, but it is not satisfactory on organic soils
without careful management. It is susceptible to frost, to the yellow sugarcane
aphid and oat green bug, and to competition from common Bermudagrass when
continuously grazed at or near its carrying capacity. It has proved inferior to
other grasses for pasture in the Everglades area and has been eliminated from
the Station grazing trials.
Suwanee and Coastal Bermudagrass require careful management on organic
soils in regard to both grazing and mowing. In the Everglades area they can
grow so rank that they smother themselves, while under grazing they are taken
over by common Bermuda, which is not recommended as a pasture grass in the area.
The improved hybrid Bermudas and Pangola may have a place on organic soils in a
system which includes mechanical harvesting for dried feed or silage along with
the pasture program.
Ryegrass is the best temporary winter grazing crop for the organic soils.
Seed is relatively low in price and usually in good supply and good quality.
It germinates and establishes a good stand rapidly if given reasonably good
moisture conditions. Most weed which may germinate at the same time can be
effectively controlled by 2',4-D,
Oat and Rye small grain varieties developed for Florida can be used and
will furnish grazing quicker than Ryegrass, but they wilZ require more careful
grazing management and may not furnish as much feed throughout the winter season.
Both the small grains and the Ryegrass can accumulate toxic amounts of nitrate
under certain conditions.
Several species and varieties of legumes can be used for temporary winter
pasture but they are not generally recommended. They are not necessary for
nitrogen fixation on organic soils, seed is relatively expensive, and the weed
problem difficult to control.
All of the recommended grasses produce an excess of forage in the summer
and are short during Winter, but they all will make good silage which can be
stored in the pasture and used when needed.
Fla. Agr. Exp. Sta. Bul #689 Roselawn St. Augustinegrass as a Perennial Pasture
Forage for Organic Soils of South Florida
Fla. Agr. Exp. Sta. Bul #662 Beef Cattle Production on Organic Soils of
Fla. Agr. Exp. Sta. Bul #630 Photosensitization in Cattle Grazing Frosted
Fla. Agr. Ekp4 Stai Bul #510A- Plants That Poison Farm Animals.