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Title: Range Cattle REC newsletter
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Title: Range Cattle REC newsletter
Series Title: Range Cattle REC newsletter
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Creator: Range Cattle Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida
Publisher: Range Cattle Research and Education Center, University of Florida
Publication Date: June 2004
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Volume ID: VID00020
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U N1VERSITY OF University of Florida, IFAS
..FLORIDA Range Cattle Research and Education Center
In ILute of Fd and an rLd Arc ural Sclnc"s June 2004
Volume 7, Number 2



Range Cattle REC Newsletter


Heifers on limpograss at Deseret Cattle & Citrus. Combining limpograss and bahiagrass
is a good combination for central and south Florida. See page 5.


Calendar of
Month
June


Events:
Date
16- 18
17


October 14
25
29


Event
FCA Annual Convention
FCA Bull Sale
Range Cattle REC, Field Day 863-735-1314
FL Santa Gertrudis Asso. Auction 863-519-8677
Lemmon Cattle Co. Auction 706-663-4970


Location
Marco Island
Marco Island
Ona
Bartow
Okeechobee


IN THIS ISSUE:


Page


Contrasting Effects of N-Fertilizer and Sludge on Soil pH and Bahiagrass ................... ...... 2
Effect of Silicon Fertilizer on Bahiagrass Forage and Seed Production ............................ 3
Feed Mineral Mixtures Year-Round ............................................. .. 3
Seed Testing Labs ............................................................. ... 4
Gator Day Exhibits Mole Cricket on the Run ................ ............................ 5
The Use of Combined Limpograss / Bahiagrass Grazing in South Florida ................... .. 5
Nursery Techniques for Production of Uniform Leucaena Seedlings for Transplanting ............... 6
Phosphorus Phytoremediation ............................................... .. 7
Smutgrass and Tropical Soda Apple Control ....................................... ..... 9

The Institute of Food and Agricultural Sciences is an equal opportunity/affirmative action employer authorized to provide research educational information and other
services only to individuals and institutions that function without regard to race, sex age, handicap, or national origin. For information on obtaining other extension
publications, contact your county Cooperative Extension Service office. Florida Cooperative Extension Service/Institute of Food and Agricultural Sciences/University
of Florida/ Larry R. Arrington, Interim Director.







Contrasting effects of N-fertilizer and Sludge
on Soil pH and Bahiagrass

In theory, acidity refers to the
concentration of active hydrogen ions (H') in a
system. It is measured by an index called pH. The
lower the pH, the more active hydrogen ions are
present and the more acid the system. A pH of 7
(as is the case for distilled water) is neutral (H+ =
OH-), and for soil a pH of 7 is too high for most
forages in Florida. A pH of 5 to 6 is slightly acidic
and satisfactory for most Florida forages to grow.
A pH of 4 is too low or very acid and will result in
poor root growth or function of most Florida
forages.
Soil acidity tends to increase with repeated
use of nitrogen fertilizer, and liming with calcium
or calcium/magnesium compounds capable of
reducing soil acidity becomes necessary. For
example, it requires 60 lb of lime to neutralize the
acidity resulting from the application of 100 lb
ammonium nitrate and 110 lb of lime to neutralize
the acidity from 100 lb of ammonium sulfate.
Increased soil acidity (pH < 5) could reduce
pasture production by more than a third, regardless
of N fertilization, and predispose the grass to
damage by soil-borne insects and grass yellowing.
In one of the long-term (5-yr) trials to
evaluate the combined effects of liming an N-
fertilization on bahiagrass pasture at the Range
Cattle REC, Ona, annual forage DM yield declined
from 4.0 T/A to 3.1T/A when 60 lb N/A from
ammonium sulfate was applied yearly with and
without appropriate liming to maintain a pH 5.0.
Corresponding annual DM yields on plots limed to
maintain a pH of 5.0 without N-fertilization and on
control plots (no lime or pH 4.3 plus no N-
fertilizer) were 2.8 and 2.5 T/A, respectively.
In addition to DM yield, we estimated the
percentage of each plot that was green, yellow or
dead and invaded by weeds every spring from
1998 to 2002 in those trials. The greatest damage
to bahiagrass pasture (up to 69% dead with weeds
and only 31% green) occurred when grass was not
limed but N-fertilized annually. When bahiagrass
was neither limed (pH 4.3) nor N-fertilized, it was
unproductive all right (2.5 T/A) but the stand did
not deteriorate in 5-yr! (95% green). Damage to


bahiagrass stand was also minimal (95-98% green)
for limed plots whether or not they received annual
N-fertilizer. We therefore concluded that the
combination of acid soil and N-fertilizer tends to
weaken bahiagrass root stolon system and
facilitate stand loss. In acid soil situations, money
is better invested first in lime to raise the pH to 5
or higher (may require a ton of lime every 3-4
years) than on N-fertilization. On the other hand,
indiscriminate use of lime on coarse-textured soils
could lead to excessive alkaline conditions and
deficiencies of iron, manganese and other micro
nutrients. Adequate liming recommendations are
based on a knowledge of the soil pH and buffer
capacity which only the soil laboratory can
provide.
In recent years, many livestock producers
applied lime-stabilized sludge to pastures to reduce
the cost of fertilizer and lime. Although lime is
added in the processing of sludge to control
pathogens, insect vectors, and odor, limed sludge
is an excellent source of slow-release plant
nutrients (especially N and P), organic matter, and
lime. During application, the pH of limed sludge
could range anywhere between 7 and 11 with the
range of N and P content of the dry material in the
range of 3 to 5%, and 2 to 4%, respectively. Four
years of repeated application of limed-sludge at the
Range Cattle REC, Ona has shown that when used
at recommended agronomic rates, bahiagrass
forage production responds wonderfully to sludge
organic fertilizer.
Like all good things, too much can cause
serious problems to the condition of pastures.
Bahiagrass roots cannot function properly to
absorb sufficient iron, manganese and other micro
nutrients when the soil pH approaches 7. Several
bahiagrass pastures in Polk, Pasco and Hardee
counties where excessive amounts of sludge were
applied repeatedly attained a soil pH of about 7
and have lost substantial portions of the grass
stand to weeds. It is easy to identify the strips on
those pastures where sludge was applied
excessively.
As a precaution for using limed sludge,
monitor soil pH every 2-3 years and alternate
sludge use with inorganic N-fertilizer such as
ammonium sulfate or ammonium nitrate. In


Page 2 of 10







extreme situations, it may be necessary to apply
elemental sulfur to recover sludge-damaged
pastures. In a pasture used for hay production in
Polk county, we observed a pH decrease from 6.8
to 6.6 over one year when sludge application
ceased and ammonium sulfate (100 lb N/A) was
used. We are beginning work with sulfur
application to reduce soil pH and will have
specific recommendations in the near future.
(MBA)

Effect of Silicon Fertilizer on Bahiagrass
Forage and Seed Production

Although silicon (Si) is not an essential
plant nutrient, it is known that fertilizer containing
Si can improve plant growth. On organic soils in
the Everglades Agricultural Area, Si has improved
production of rice and sugarcane and inclusion of
Si is a regular production practice. In the soil,
presence of Si positively influences soil physical
properties, especially retention of phosphorus.
Laboratory and greenhouse studies at Ft. Pierce
have shown that Si fertilizer resulted in greater
root and shoot growth of bahiagrass seedlings
grown on sandy soil. However, field studies on Si
fertilization of bahiagrass have not been
conducted.
We conducted a 2-year, replicated study on
Argentine bahiagrass forage and seed production
at Rhode Ranch near Yeehaw Junction. A
different plot area within the same pasture was
used in each year. Treatments were single
applications of 0, 0.9, 1.8, and 3.6 tons/acre of Pro-
Sil, which is a bi-product of processing steel slag.
Pro-Sil contains -14% Si, 30% calcium (Ca), 55%
magnesium (Mg). Bahiagrass was fertilized once
annually in May with a complete fertilizer which
supplied 60-30-50 lb/acre of N-P205-K20,
respectively. Micronutrients were also included in
the fertilizer. Pastures were grazed except the
period from June through August to allow for seed
production and harvest. We measured bahiagrass
forage production in May and June and seed yield
in August.
Fertilization with Si had no effect on
Argentine bahiagrass forage production, which
averaged (2 year) 1100 and 3300 lb dry


matter/acre for May and June, respectively. Seed
yield was not affected by treatment and averaged
130 lb/acre. Concentrations of Ca, and Mg in the
soil increased as rate of Pro-Sil increased, but
concentrations of all other elements in the soil
were not affected. Concentrations of all elements
in bahiagrass forage were not affected by
treatment.
Results from this research indicate that Si
fertilization did not improve bahiagrass forage or
seed production under field conditions at this one
location. Because conditions differ throughout
Florida, it is possible that Si fertilization results
could differ elsewhere. (RSK, VM, MBA)

Feed Mineral Mixtures Year-Round

Even when we have low cattle prices, one
input a rancher should not cut back on is mineral
supplementation. A good mineral supplementation
program should cost about $7 to $9 per cow
annually. This is a very low-cost insurance policy.
Research shows that perennial grasses
grown in south Florida requires less phosphate
fertilizer than previously recommended. In fact,
phosphate fertilization is not recommended for
bahiagrass in south Florida. Fertilization research
shows that phosphorus is 20 to 25% lower in
bahiagrass forage not fertilized with phosphate.
With modern fertilization practices it is very
important that a good mineral supplementation
program be followed.
Other mineral nutrients deficient in forages
grown in south Florida include copper, cobalt,
zinc, iodine, manganese, magnesium, and
selenium. Even if minerals are not needed in every
situation, the amounts added to a mineral mixture
is low and the added cost is minor. Also,
borderline deficiencies of trace elements may be
present in the forage which could affect cow
reproduction and/or calf growth, and the problem
not visually recognized.
A mineral mixture has been developed over
many years and fed at the Range Cattle REC. It is
periodically reformulated and the current mixture
contains 14% calcium, 9% phosphorus, 23% salt,
0.20 % potassium, 0.30% magnesium,1500 ppm
copper, 50 ppm cobalt, 3000 ppm zinc, 210 ppm


Page 3 of 10







iodine, 500 ppm manganese, 40 ppm selenium, and
180,000 USP units of vitamin A per pound. This
mineral mixture is fed at a rate of 2 ounces or
0.125 pound per head per day to cattle grazing
sandland pastures. Costing $300/ton, annual cost
is $6.85/cow.
There is nothing magical about the Range
Cattle REC mineral formula. Other mixtures that
provide similar quantities of the mineral nutrients
known to be limiting in south Florida forages are
equally as good. The important thing is to provide
cattle with mineral year-round and watch out for
cost.
One cost saving measure is to prevent over
consumption. Some formulas are very palatable
and cattle will eat two or three times more than
needed if fed free-choice. Intake can be controlled
by placing a measured quantity of mineral in the
feeder for a specific number of cattle for a specific
time period (for example three weeks). If cattle
eat all the mineral before the next feeding it will
not cause problems. Excess minerals are stored in
bones, liver and other tissues, and will provide for
the animal's needs over several days or even
weeks when mineral is not available. However,
you don't want cattle to consume all the mineral
mixture during the first few days after it is offered.
At the other extreme, cows may eat little or
no mineral mixture for long periods, often months.
The formulation of the mineral mixture may need
to be changed to encourage intake. This is often
accomplished by increasing the percentage of the
palatable component, such as cottonseed meal,
citrus pulp, cane molasses, or similar ingredients.
Low mineral intake can result from high salt
content in the drinking water, and the salt level in
the mineral mixture may need to be reduced.
Work with your mineral mixture supplier
and a good formula which supplies adequate
quantities of mineral nutrients at a reasonable cost
can be accomplished. (FMP)

Seed Testing Labs

Seed that you buy in Florida has a tag that
provides percentage germination. To be valid, the
date of purchase must be within 7 months of the
date of test. If you are planting a large acreage of


pasture, it is a good idea to do your own seed
testing as a check. Test your seed before you put it
in the ground. If you have many bags of seed, try
to sample at least 20% of the bags. For example,
if you have 20, 50 lb bags of bahiagrass, then you
need to sample four bags selected at random. Take
a "handful" of seed and put it in a zip-lock bag
along with a slip of paper containing your name,
address, phone number, plant ID (Pensacola
bahiagrass), and seed lot number found on the bag
you purchased. Here are two choices for seed
laboratories:

Florida Dept. of Agric. and Consumer Services
Bureau of Feed, Seed & Fertilizer Laboratories
3125 Conner Blvd. Bldg. #4. Seed Lab.
Tallahassee, FL 32399-1650

phone: 850-488-9095
fax: 850-410-5342
email: chasonw(@doacs.state.fl.us
web site: http://doacs.state.fl.us/-aes-fsflab

Mr. Wallace Chason is in charge at the
state lab. This lab will test seed of all of the
common forages we sow. For example, bahiagrass
costs $21; aeschynomene and ryegrass are $15.75
/ sample. If you visit their web site above you can
get information about the lab including forms for
sample submission. If you don't have access to the
Internet, you can call or fax to get forms before
you submit your sample. Forms are not essential,
but be sure to include all the information listed
above with the sample. Do not prepay as an
invoice will be included with the results.

Hulsey Seed Laboratory
P.O. Box 132
Dacatur, GA 30031-0132

phone: 404-294-5450
fax: 404-294-TEST

Mr. Jerry Hulsey is in charge at this private
lab. They will test most of the common forages
we use in Florida. For example, Argentine
bahiagrass is $20; Pensacola bahiagrass is $15;
aeschynomene is $14; and ryegrass is $13 /


Page 4 of 10







sample. With Hulsey, just send your sample to
them with your name, address, etc., and they will
bill you. (RSK)

Gator Day Exhibits Mole Cricket
on the Run

Each year, UF/IFAS takes exhibits to the
Florida Capitol for "Gator Day", showcasing UF
/IFAS programs for the Florida Legislature in
Tallahassee. This year, the UF/IFAS Marketing
Council invited the statewide "Biocontrol Mole
Cricket Project", among six selections, to
participate in the Gator Day Exhibits program.
Two 6' x 3' banner posters were developed
and presented at the Capitol. The first highlighted
the problem of mole cricket infestation on
bahiagrass pastures and the patented biocontrol
solution developed by UF/IFAS. The second
depicted successes achieved with state funds in
transferring that technology throughout Florida.
And there was the video projection of live mole
cricket nematodes from a microscope on a rear
projection screen situated between the two posters
to draw the crowd.
Briefly, non-native mole crickets damage
pastures, golf courses, turf fields and urban
landscapes and cause -$100,000 loss (reduced
crop yields, chemical controls, grass renovation)
annually. The mole cricket nematode (Steinernema
scapterisci) was developed specifically to control
pest mole crickets and do no harm to non-target
organisms. Between 2001 and 2002 the Florida
Legislature provided $300,000 in state funds to
support a statewide educational effort on mole
cricket biocontrol. These funds were used to 1)
establish a commercial production source for the
mole cricket nematode Nematac S produced
by Becker Underwood, 2) demonstrate the efficacy
of reduced nematodes strip-application rates
statewide by distributing 65 billion nematodes in
34 Florida counties, 3) establish a commercial
source of custom strip-application by Ingram
Grove services, Inc. and 4) assemble and educate
a network of vendors for handling and marketing
of the product to producers.
For $25/acre product cost and $10/acre
for custom application fee, the nematodes have


proven to provide long-term suppression of pest
mole crickets on bahiagrass pastures to sustain
beef production. It is not surprising that the
consignment ofNematac S for spring 2004 was
sold out early in March. The next batch will be
ready for market in September 2004 and interested
producers need to contact their county livestock
agents for ordering information.
The Gator Day exhibit on "Mole Cricket on
the Run" at the Capitol on April 14, 2004
generated appropriate enthusiasm from the
Legislature, producers, IFAS administration and
even school children. I extend a thank you to Dr.
Pate who funded the cost of the exhibit and Lockie
Gary, Hardee Co. Extension Director, who assisted
to mount and supervise that booth. (MBA)

The Use of Combined Limpograss /
Bahiagrass Grazing in South Florida

First extensively evaluated in 1974,
'Floralta' limpograss is the most widely utilized of
the available limpograss varieties in south Floirda.
This tropical grass originates from the Limpopo
River in the Republic of South Africa. Floralta is
a stoloniferous perennial tropical grass that was
specifically selected for persistence under grazing
conditions. Common to the limpograsses, Floralta
produces very little seed and is therefore
established vegetatively.
The need to identify forages that will
provide adequate dry matter yield in the winter
months is of major importance to south Florida
cattlemen. A 1998 survey of south Florida
cattlemen revealed that 79% of beef operations
fed stored forage in the winter months. Floralta has
superior winter yield compared to other warm
season perennial grasses. In south Florida,
limpograss can be expected to produce as much as
30 to 40% of its annual growth in the winter
months. One distinct characteristic of Floralta is
the ability to maintain appreciable levels of TDN
at later stages of maturity. Limpograss maintains
nearly 59% TDN, even after 10 weeks ofregrowth.
Compared to bahiagrass, Floralta limpograss
provides appreciable dry-matter yield and is highly
palatable. Floralta holds considerable potential as
a fall/winter stockpiled pasture forage for south


Page 5 of 10







Florida cattlemen.
We have recently completed a three-year
study investigating the effect of replacing
supplemental winter hay with stockpiled
limpograss on cow and calf performance. Sixty
acres of limpograss were established in the
summer of 1999 for use in a combined bahiagrass
/ limpograss rotational grazing study. Cows
assigned to the limpograss / bahiagrass rotation
were provided 0.75 acres/cow of limpograss and
1.50 acres/cow of bahiagrass in a modified
rotational grazing system. Cows assigned to
bahiagrass alone (Control) were provided 1.80
acres/cow of bahiagrass. Supplemental winter hay
was provided to the Control cows in an attempt to
maintain adequate cow body condition during the
winter. All pastures received a spring application
of 60 lb N/acre. Limpograss pastures also received
an additional fall application of fertilizer (60 lb
N/A). During September, October, and November,
cows assigned to the bahiagrass / limpograss
combination treatment were grazed primarily on
bahiagrass alone allowing the limpograss to
stockpile for winter utilization.
All cows were provided 5 lb supplemental
molasses (16% CP) daily from November 1 to
mid-April. A 90 day breeding season was initiated
on January 1. Pregnancy was determined by rectal
palpation in July of each year. Calves were weaned
during the first week in August each year.
Cows grazing winter limpograss pastures
were provided with no winter hay compared to an
average of 1400 lb/cow provided annually to
Control cows during the winter feeding period
(January to late March). Cows assigned to the
limpograss treatment lost an average of 26 lb, but
gained an average of 33 lb more body weight
during the winter and summer months compared to
Control cows receiving supplemental winter hay.
Grazing treatment had no effect on calf weaning
weight (average weaning weight = 547 lb).
Pregnancy rates were also not affected by grazing
treatment (average over all three years = 92.2 and
91.6 % for Control and limpograss cows,
respectively).
Initially, it appears that grazing strategies
that incorporate stockpiled limpograss could be
economically effective for fall calving beef cattle


in south Florida. Even though limpograss has
appreciable winter yield, the majority of growth
occurs during the summer rainy season. Cows
assigned to the limpograss / bahiagrass treatment
spent much of June and August exclusively
grazing limpograss. An important consideration to
this management strategy suggests that limpograss
may limit calf growth compared to bahiagrass, as
pre-weaned calves grazing summer limpograss
gained an average of 11 lb less than those grazing
bahiagrass during the interval from April to
August. An economic analysis of both pasture
systems is appropriate for each individual ranch.
Calving seasons that differ from those used in this
study may have a significant impact on the value
achieved from the limpograss. As well, persistence
of stand will greatly impact economic return, as
the high-cost oflimpograss establishment is spread
over greater or fewer production seasons. (JDA &
FMP)

Nursery Techniques for Production of
Uniform Leucaena Seedlings for
Transplanting

Leucaena is a leguminous tree legume that
can provide nutritious forage for cattle, meat goats,
and in wildlife plantings in Florida. It is a tropical
plant that is adapted to fertile, well-drained (not
less than pH 6.0) soils. Leucaena can be
established by seed or transplanted seedling but the
latter gives better and more uniform field survival.
Rapid early growth ofleucaena is highly desirable
because it cuts down on the need for weed control,
and enables the plant to successfully compete with
weeds, and exploit improved planting site
conditions. The procedures we use to produce
seedling for our field plantings are outlined.

Seed treatment
Scarification
Hot water: Leucaena seed has a hard seed coat
that prevents it from absorbing water and
germinating. Scarification involves breaking the
seed coat to permit water imbibition. We have
used hot water and manual scarification with about
the same level of success (>90% germination).
Pour hot water over seeds in a suitable container,


Page 6 of 10







stir and leave standing for 2 minutes. The amount
of water used should be about five times the
amount of seed. After 2 minutes, decant water, and
dry seed, if you are not treating with rhizobium
immediately. Hot water treatment may be
combined with soaking overnight. By soaking
overnight, seed that were successfully scarified,
imbibe water and swell. This way one can plant
out seeds that had been scarified. For large seed
lots, small batches (-0.5 lb) of seed may be treated
at a time. Leucaena seed can be obtained from
ECHO (Educational Concern for Hunger
Organization: 239-543-3246); and COSAF (Center
of Sustainable Agroforestry: 352-376-6265).
Manual scarification: For more than 1 lb
of seed, manual seed scarification may be too
tedious. The broad end of the seed is nicked with
a file, knife or nail clipper. Be careful not to cut
the cotyledon (or your finger tip!). Overnight
soaking is not necessary with this method.

Rhizobium inoculation
Like most legumes, leucaena can use
atmospheric nitrogen for its growth through a
symbiotic relationship with some bacteria called
Rhizobium. Successful infection of a plant is
evident from the formation of nodules on the plant
roots. Leucaena requires the specific rhizobium
that it associates with to be present in the soil
otherwise its growth may be stunted and leaves
appear pale in color. When leucaena is to be
established where leucaena had grown before, new
inoculation may not be necessary since the bacteria
will be present in the soil. Peat cultures of
leucaena rhizobium can be obtained from Nitragin
Inoculants (414-462-7600). Pour some of the peat
culture into a bowl, add water as required to make
a slurry or paste. Pour in the seed and stir. The
objective is to uniformly coat the seeds with the
slurry, air dry (if not planting out immediate) and
the seed is ready for sowing. Soil from under
established stand of leucaena can also be used as
source of inoculum.

Preparation of potting substrate
Materials needed:
1. Potting mixture: We use Fafard 4-Mix
Professional Formula. We buy from Southern


Agricultural in Palmetto, FL (941-722-3285).
2. Complete fertilizer: We use Osmocote
(18-6-12), a controlled release fertilizer and
Essential Minor Elements. Both are obtained
from Southern Agricultural.
3. Elemental sulfur. We add this to keep pH
from becoming too high because our irrigation has
large amount of calcium and magnesium
carbonates.
4. Container: We use Multi-Pots #3-96
flats, with 96, 6-cu. in. cells from Stuewe & Sons,
Inc., 2290 SE Kiger Island Drive, Corvallis,
Oregon 97333-9425. (1-800-553-5331).
For each bag (2.8 cu. ft.=79.3 L), we add 9
g sulfur, 80 g micronutrient mixture, and 204 g of
Osmocote. This is thoroughly mixed in a cement
mixer. One bag of Farfard mix will fill 7 flats. A
little pressure is required on the mixture when
filling into the cells to firm the substrate. It is also
helpful to add some water to get a good
consistency that will make filling the cells easier.
After filling the cells, the scarified and inoculated
seeds are sown, one per cell, and the flats set on
level surface in a nursery shed. Daily watering will
be required. It is helpful to have your irrigation on
a timer and keep the flats moist.
It may take 3 to 4 months for the seedlings
to reach 8-12 in. when they can be handled without
much damage. At this stage they can be
transplanted in the field. Leucaena established
better on well-prepared, fertilized and limed (if
necessary) soils. The seedlings can be transplanted
into the field in June-October. When transplanting
into established pastures, leucaena seedlings
should be transplanted into 2 to 3 ft. wide strips
that had been rotovated and well-fertilized. (IVE
& RSK)

Phosphorus Phytoremediation

Amounts of manure generated by
concentrated animal operations often exceed the
carrying capacity of nearby land, and stricter
environmental regulations lead to creation of
pockets of highly impacted sites within a
watershed basin. Manure utilization for forage
production can be an effective approach for
addressing both the problems of manure disposal


Page 7 of 10







and impact reductions on water quality. In general,
cropping patterns, climate, topography, and
fertilization practices affect concentrations of
nutrients, including N and P, in runoff waters.
Forage production systems may not only be
environmentally sound for recycling of nutrients
and minimizing nutrient loss to water bodies, but
they may also help farmers/producers to maintain
a profitable business enterprise.
In concentrated animal operations, feeds are
transported to the farm while a lack of manure
transportation from the farm results in a net
accumulation of nutrients. This can create
pockets of highly impacted sites within some
ranches/farms. A case in point is the Lake
Okeechobee Basin. Phosphorus has been identified
as a major cause of eutrophication of Lake
Okeechobee. Hence, the efforts for water quality
improvement in the lake have primarily been
aimed at fertilizer and animal waste management
in the basin.
Animal manures can be effective sources of
nutrients for forages, and their applications to
pastures could provide substantial amounts of
nutrients, such as N and P, recycled through
herbage production. High quantity and quality of
herbage can be produced on impacted sites
although optimal management of forage
production and manure is crucial.
Unlike commercial inorganic fertilizers,
manures have the disadvantage of not having the
right nutrient forms and/or ratios for specific
crop/forage requirements. Thus, their use may lead
to accumulations of excess nutrients including N
and P in soils, and cause potential hazards to water
quality. As eco-consciousness increases,
developments of environmentally and
economically sound agricultural production
systems are receiving high priority around the
world. To reduce potential threats from nutrient
runoffs and leaching effects on water quality,
recycling nutrients through forage production
systems may provide attractive alternatives to
farmers/ranchers to comply with environmental
rules and regulations, especially in the region
where ecologically sensitive water bodies exist,
including the Lake Okeechobee Basin.
Various animal manures including cow and


poultry manures have been used to fertilize
pastures in the US and around the world. Although
animal manures are usually targeted at crop/forage
production, the nutrients from manures often move
in substantial quantities from the targeted
agricultural parcels to aquatic systems through
runoff and leaching. Such scenarios may cause
undesirable changes, directly or indirectly both to
agricultural parcels and the nearby water bodies.
In general, non-point sources such as
agricultural runoffs are considered major sources
of P to surface waters of the US. Intensive forage
production can deplete P levels in highly
manure-impacted soils, and such forage production
may represent a crucial component of nutrient
management in pastures. Differential P uptake by
various forage species are expected depending on
the forms of P present in soils and the capacities of
the plants to mine the relatively stable P. Surface
applications of slurry and mineral fertilizers in
soils with low levels of P may significantly
increase P level in the soil surface. Hence P
loading to the surface runoff could increase
sharply.
Proper estimation of P requirements is
possible only if existing P availability in soils is
determined. And, it is critical to reduce P losses in
runoff due to over fertilization. Once the P
demands of grasses in pastures/grasslands are met,
the efficiency of grasses in removing/utilizing P
usually decreases drastically. Different grasses
have variable capacity to remove nutrients.
Nitrogen and lime applications are very important
for optimal herbage production as well as P uptake
by plants. Thus, it is important to know how much
lime to apply for various N rates and sources in
order to maintain optimal soil pH.
Although animal manures may not have the
right forms of nutrients in the right ratios for
specific forage requirements, they can be used as
nutrient sources, and recycled through herbage
production. It is important, however, to optimize
nutrient uptake, especially ofP by specific forages
from a given impacted site. Such herbage
production may not only be environmentally sound
due to recycling of nutrients and reductions in their
losses to ecologically sensitive water bodies, but it
may also help farmers/producers to maintain


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long-term economic profitability. As there is a
critical need for the understanding of P dynamics
in pasture systems established in P-enriched areas,
we, at the University of Florida, Range Cattle
Research and Education Center in cooperation
with the Agronomy Department, have set up an
experiment at Butler Oak Dairy in Okeechobee
with a grant from FDACS to determine whether
the widely used forages in southern Florida (i.e.,
bahiagrass, limpograss and stargrass) can actually
be used for P phytoremediation of manure-laden
soils in the region. (HKP & MBA)

Smutgrass and Tropical Soda Apple Control

Florida pastures contain about 0.5 to 0.75 million
acres of smutgrass and tropical soda apple (TSA).
These two plants are probably the most serious
weeds in Florida pastures.

Smutgrass
Basically there are two species of
smutgrass found in Florida 1) small smutgrass
(Sporobolus indicus) and 2) giant smutgrass or
West Indian drop seed (Sporobolus pyramidalis).
Many times these two types of smutgrass are found
growing together in pastures. It is important to be
able to identify the two types of smutgrass because
treatment is different for each type. The main
characteristic for identification is the length of
branches on the head. The smaller smutgrass has
short branches about 0.5 to 1.0" long and generally
are found stuck together forming a single spike.
The giant smutgrass has an open type head with
ascending branches 1.5 to 2.5" long. The height of
the plant has nothing to do with the type of
smutgrass found in the pasture. Studies have
shown that 'Velpar' applied at 0.5 to 0.75 lb/A
active during the rainy season of July and August
will provide 90% + control of the small smutgrass.
Velpar applied at 1.0 lb/A during the rainy
season will provide 88-90% control of the giant
smutgrass. Both rates of Velpar require a silicone
sticker at 10oz/100 gal. water. No pre-herbicide
mowing of smutgrass is required. Velpar is most
desirable for controlling smutgrass in bahiagrass.
Special precautions must be used when controlling
smutgrass in hemarthria. Do not spray stargrass


with Velpar. Velpar may cause bahiagrass to
turn yellow 20 days after treatment but plants will
turn dark green again after 40 days. The
application of Velpar rates higher than 1.0 lb/A
is harmful to bahiagrass. Remember, Velpar will
kill oak trees.

Tropical Soda Apple
Tropical soda apple is a broadleaf,
perennial, noxious weed that has spread rapidly
throughout Florida and other southeastern states.
Mature plants range from 4 to 6 ft and produce
nearly all their fruits from August through March.
Germination and development of seedlings are
greatest between August and March. Tropical soda
apple is identified by its immature green fruit with
white mottling like the fruit of many cultivars of
watermelon. Mature fruit turns yellow and may
contain 400 to 500 seeds each. Studies have shown
that TSA plants can be controlled by several
methods. 1) Application of Remedy at 0.5 lb/A
twice at 60-day intervals provided 98% control to
non-mowed TSA plants. 2) Remedy applied at
1.0 lb/A (one time) to non-mowed TSA plants
provided 88-90% control. 3) TSA plants mowed
and allowed 60 d regrowth, then sprayed, always
provided better control than non-mowed
treatments. Therefore, mowing TSA plants one
time, allowing 60 days regrowth followed by 0.5
lb/A Remedy provided 98% control. 4) Mowing
TSA plants 2 or 3 times at 60 d intervals followed
by 0.5 lb/A Remedy provided 100% control. 5)
Mowing TSA plants to a 3-inch stubble 1, 2, or 3
times at 60-day intervals provided 10, 67, and 92
% control, respectively with no herbicide. 6)
Spraying TSA 60 days after the last freeze with 1.0
lb/A Remedy provided 97% control and saved
$10 to 15 /A mowing costs. 7) Spraying TSA 60
days after the last freeze with 1.0 lb/A Velpar
(plus rain) provided 98% control of TSA plus
control of smutgrass and dog fennel while saving
$10 to 15 /A mowing costs. All Remedy
treatments should be applied with a silicone
surfactant at 10 oz/100 gal. water. If additional
information is desired please call 863-735-1314.
(PM)


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CONTRIBUTORS:


Rob S. Kalmbacher, editor
Martin B. Adjei
John D. Arthington
Paul Mislevy
Findlay M. Pate
Ike V. Ezenwa
Hari K. Pant
Vladimir Matichenkov


Page 10 of 10




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