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Production of corn for silage
Silage additives and silage quality
Making, storing, and feeding silage to beef cattle
Small grain and alfalfa silage
Chemical-assisted drying and fall grazing of Florida 77 alfalfa
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
site maintained by the Florida
Cooperative Extension Service.
Copyright 2005, Board of Trustees, University
SResearch Report NF 83-2
FALL FORAGE FORUM
SI LAG E
PROCEEDINGS FIFTH ANNUAL
JUL 1 0 I3
IFAS. Univ. of Florida
NOVEMBER 1, 1983
INSTITUTE OF FOOD AND AGRICULTURAL SCIENCES
UNIVERSITY OF FLORIDA
J. T. Woeste, Dean for Extension
F. A. Wood, Dean for Research
-.r ^ ^ [
Proceedings of the Fifth Annual
Fall Forage Forum
The topic of this years program is silage production. Those
speaking on the subject have many years of experience in research
or have practical farm experience on putting up large quantities
The speakers will cover subjects from growing different
crops for silage to harvesting, storing, and feeding.
D. L. W ight
Speakers on the program are as follows:
Fred Rhoads University of Florida, Quincy, AREC
Marshall McCullough University of Georgia, Georgia Station
Sloan Baker University of Florida, Quincy, AREC
Ray Bassett Jefferson County, Dairy farmer
Ed Golding University of Florida, Quincy AREC
PRODUCTION OF CORN FOR SILAGE
F. M. Rhoads
Fall Forage Forum
Corn silage is a high quality feed for beef and dairy animals. Corn
yield of 100 bu/A will produce 1540 Ib of beef per acre when fed as silage
and 958 Ib per acre when fed as high moisture ground ear corn (Aldrich,
Scott, and Leng, 1975). This suggests a market value for corn silage
equal to 1.5 times the value of the grain it contains. The feed value de-
pends upon total dry matter production and not just the grain yield.
The ideal moisture content for preserving corn silage is 60 to 65%
(Aldrich, et al. 1975). A 100 bu/A grain crop of corn produces about
11,200 Ib/A of dry matter or 16 tons of wet silage per acre. In order to
convert bushels of grain to tons of silage multiply by 0.16.
Maximum profits are obtained when yield is at the level to achieve
minimum production cost per ton of silage. Fortunately this occurs at near
the maximum potential yield for corn.
There are many factors that influence yield levels of corn. Among
those factors that can be controlled by the grower are water, nutrients,
hybrids, population row spacing, planting date, weeds, insects, and some
diseases. This paper is mainly concerned with water and nutrients, however,
some brief comments are included on hybrids, population, row spacing, and
Effect of Soil Water Management on Corn Production
Corn yield is reduced by periods of dry weather in this area during
most years. Total annual rainfall is more than adequate to produce maximum
yields. Therefore, water is available for storing and applying to the crop
in the form of irrigation. Research has shown a yield increase for corn from
12 bu/A on dryland to 160 bu/A under irrigation. Needless to say, silage
was of poor quality with only 12 bu of grain/A. Furthermore, nitrates can
accumulate in corn silage under drought conditions. Nitrate in cattle feed
can cause death if levels get high enough.
Water use efficiency of corn has been reported to range between 5.9
bulacre-inch and 13.8 bu/acre-inch (Viets, 1966). This is equivalent to 0.9
and 2.2 tons of silage/acre-inch. Highest grain and silage yield occurred in
an irrigation experiment when the plow layer was recharged at the soil water
suction value of 20 centibars (cb). Irrigation water use efficiency (IWUE)
remained high even though irrigation was required every three days during
the flowering and filling period (Table 1).
Table 1. Response of corn to irrigation applied at various levels of soil
water suction (AREC, Quincy).
Soil water Irrigation Yield IWUE
suction cb applied (in) Grain (bu/A) Silage (ton/A) Bu/in Ton/in
20 8.7 190 30.4 8.6 1.38
40 7.1 175 28.0 8.5 1.36
60 4.7 160 25.6 9.6 1.54
-- 0 115 18.4 ---
Irrigation cost for a 138 acre center pivot system is $12.25 per acre-
inch of water (Eason and Rhoads, 1983). Value of 8.5 bu of corn at $3.50/
bu is $29.75 for a profit of $17.52 per acre-inch of irrigation. The equiva-
lent amount of silage would be worth approximately $45 for a profit of $32.75
per acre-inch of irrigation.
Scheduling irrigation to produce high corn yields under a center pivot
system requires application of 1-inch of water when tensiometers placed at
the 6-inch depth read 20 cb of suction on sandy soils of the Southeast.
Tensiometer stations should be located at the middle and outer edge of the
pivot with one on each side of the normal stop position for a total of four
Effect of Nitrogen on Corn Production
Nitrogen is the most expensive plant nutrient in terms of dollars per
acre, but yield response is most consistent for this element because of
low residual carryover from year to year. More than 30 tons of corn silage
per acre were produced with less than $50/acre nitrogen cost (Table 2).
Highest yield was produced with 240 Ib of N/A.
Table 2. Response of irrigated corn to nitrogen fertilization with 36,000
plants per acre.
Fertilizer Grain Silage N-cost Silage value
Ib-N/A bu /A ton/A $/A1/ $/A-
0 65 10.4 0 341.25
80 164 26.2 23.53 861.00
160 210 33.6 47.06 1102.50
240 231 37.0 70.59 1212.75
400 231 37.0 117.65 1212.75
1/Based on price of ammonium nitrate at $200/ton.
2Based on price of grain at $3.50/bu.
Effect of Phosphorus and Potassium on Corn Production
Production costs can be reduced if soil tests are utilized to avoid ex-
cessive application rates of P and K. Excessive rates are defined as appli-
cation levels above which no further yield increase occurs.
Highest yield of irrigated corn was obtained with a soil test level of 160
Ib of P205/acre and the application of 120 Ib of P205/acre as 46% superphos-
phate (Table 3). Total phosphorus uptake was not increased by application
of 240 Ib of P205/acre. Phosphorus (P205) uptake by corn was about 0.7
Ib per Ib of soil test P205. The soil test P205 level required to achieve the
maximum uptake shown in the table is 185 Ib/acre.
Table 3. Response of irrigated corn to soil test plus fertilizer phosphorus
Soil test Fertilizer P20 5 Grain Silage
P205 P205 uptake bu /A ton /A
80 0 57 99 15.8
109 60 111 176 28.2
160 120 129 224 35.8
210 240 129 218 34.9
Potassium fertilization not only increased corn yield, it also reduced
lodging (Table 4). Reduction of lodging increases harvested yield even if
total yield remains the same. Machine harvested yield could have been as
much as 63% less than total yield with no K added as fertilizer. The correl-
ation between soil test K20 and yield was not significant with the application
of either 225 or 450 Ib of K2O/A.
Table 4. Response of irrigated corn to soil test plus fertilizer potassium.
Soil test Fertilizer K20 Lodging Grain Silage
K20 K20 uptake % bu/A ton/A
120 0 115 63 164 26.2
190 225 229 4 190 30.4
230 450 264 12 224 35.8
The additional cost of 225 Ib of K20 for the highest yield is $33.75 and
the value of the 34 bu/A yield increase at $3.50/bu is $119. The increase
in silage value is about $178.
Soil fertility is depleted much more rapidly when corn is produced for
silage than for grain because the whole plant is harvested. About 30% of the
total phosphorus taken up and 80% of the potassium is removed in the stalk
(Potash and Phosphate Institute, 1972). Therefore, it takes five times as
much K fertilizer to replace what is removed in silage than in grain.
Hybrids, Population, Spacing, and Planting Date
There can be large differences in yield potential between hybrids.
Growers should consult reports from state variety trials when selecting hy-
brids for high yield.
Low population can limit corn yield and so can improper row and plant
spacing. High populations are subject to lodging and also a lower grain/
dry matter ratio. Best population range for silage production appears to be
30,000 to 35,000 plants per acre. Narrow rows with near equal distant
spacing between plants are more ideal for high yield. Row spacing of 30
inches is perhaps most practical for available harvesting equipment. A double
row system also works well.
Early planting is recommended but cold damage can result if planting
is too early. Mid-March is a good target date for planting corn for high yield
in this general area. Late planting results in excessive insect and disease
1 Aldrich, S. R., W. O. Scott, and E. R. Leng. 1975. Modern corn pro-
duction. A and L Publications Champaign, IL. p. 303-315.
2 Eason, M. A., and F. M. Rhoads. 1983. Economics of irrigation scheduling
for field corn in North Florida. Univ. of FL, Quincy AREC Res. Rpt.
3 Potash and Phosphate Institute. 1972. Plant food your corn takes up
while it grows. Circular. Atlanta, GA.
4 Viets, F. G., Jr. 1966. Increasing water use efficiency by soil manage-
ment. In: W. H. Pierre, Don Kirkham, John Pesek, and Robert Shaw.
(Eds.). Plant environment and efficient water use. Amer. Soc. Agron.
and Soil Sci. Soc. Amer. Madison, WI, p. 259-274.
Silage Additives and Silage Quality
M. E. McCullough
Georgia Station, Experiment, GA 30212
Silage quality has an air of mystery about it that is not necessary.
The same can be said for all forages that are used as primary feedstuffs
for dairy and beef cattle. Fundamentally, quality only means those items
that control the usefulness of the hay or silage as a feedstuff for a
particular feeding program. About all of the term quality can be defined
by the equation:
Quality = % digestibility X pounds intake
In short, quality is really the amount of digestible energy or protein
or fiber or whatever it is the forage is to be used for. For some reason,
quality is more likely to be equated with protein even in silages such as
corn or sorghum which are primarily used as energy sources. This is
unfortunate since it prevents a true evaluation of the silage.
Since we are looking for all of the digestibility we can get at a
stage of harvest that also gives us an economical amount of forage, the
starting point in quality is stage of harvest. Everyone grows high quality
forage; many fail to harvest it at the stage when it is high quality.
In Georgia, after some 28 years of silage research, we recommend the
following stages of growth as the optimum harvesting times:
a) Corn silage dent stage
b) Sorghum silage (forage type) early heading
c) Sorghum silage (grain type) dough stage
d) Legumes early bloom
e) Grasses early heading
Having grown a good crop and harvested it at the proper stage of
maturity, we can consider the subject of additives as one management
tool to insure our keeping the forage quality we ensiled.
Silage usage in the United States is about 100 years old. For
99 of those years, someone has been selling something to add to that
silage. Many people have been quite certain that you should be able
to influence the fermentation in the silo in a positive manner. Of
the dozens and dozens of products that have been sold to be added to
forage being ensiled, only a very few have been worth the cost in money
and labor. Those that work have done so by altering the fermentation
to increase the speed of lactic acid formation in the silo. When this
happens, the total amount of heating is reduced with a resulting savings
of dry matter. This is measured by greater dry matter recovery and by
an improved savings in the energy value of a unit of silage. As a good
general rule for southeastern silages, silage without an additive will
have total dry matter losses of 10-15% and those with a good additive
a loss of 5-7%. In the case of dairy cows at peak lactations, this has
increased daily milk production from 77.3 Ib/day for untreated silage
to 81.0 Ib/day for treated silage (3-year average of Wisconsin data).
There are two classes of additives (aids to fermentation) that
have procen useful in University research.
a) Bacterial cultures. This type of product is useful only
when the bacteria have been selected to be used in silage
and when they are alive when ensiled.
b) Enzyme mixtures. These products increase rate of fermen-
tation by increasing the growth rate of bacteria already
on the silage. Again, the enzymes must be selected to
be active in the pH ranges and at the temperatures en-
countered in ensiling southeastern forages. In general,
good aids to fermentation have given better responses in
the southeast than in other areas of the country. This
probably reflects the higher atmospheric temperatures in
this area and the generally greater problems we have in
Truly great silage of high quality suitable for dairy cows and
growing cattle are a combination of harvesting crops at the optimum
stage of maturity and doing a good job of keeping that quality during
the ensiling stage. Remember, the silage that comes out of the silo
(any silo) has less feeding value than the forage that was ensiled.
Proper harvesting and a good additive can keep this loss to a minimum.
MAKING, STORING, AND FEEDING SILAGE
TO BEEF CATTLE
Agricultural Research and Education Center
Route 3, Box 638
Quincy, Florida 32351
Silage is a fermented feed, stored in a silo (trench or
bunker, upright, or simply piled in the open) at high moisture.
The moisture is necessary to make it possible to pack the silage
and to exclude air so that anaerobic (without oxygen) fermenta-
tion can take place. Moisture contents of various silages
generally are within the following ranges:
Silage From To
Corn 60 72 (65 ideal)
Sorghum (silage) 65 75 (70 ideal)
Oats 70 72
Wheat 72 75
Millet or sorghum-sudan 72 77
Haylage (wilted) 35 55
ALL THE NUTRIENTS IN SILAGE ARE IN THE DRY MATTER.
To determine percentage of dry matter subtract percentage of
moisture content from 100. For example:
Dry matter Lb dry matter
100 minus Moisture Content (%) = Content (%) per ton
Corn silage 65 35 700
Sorghum silage 70 30 600
Coastal Bermuda hay 9 91 1820
Although silage dry matter may contain high levels of
nutrients, such as total digestible nutrients (TDN), the water
content in the silage dilutes the nutrients on an as-fed basis.
With mature cattle on a maintenance ration, the high moisture
content may not be a problem, but with young cattle being back-
grounded, the high moisture may limit feed consumption and thereby
restrict gains, as will be discussed later.
MAKING, STORING, AND HANDLING SILAGE
1. Harvest at proper stage of maturity.
Dent stage for corn
Dough stage for sorghum before grain gets hard
1/ Presented at Fall Forage Forum, Quincy, Florida, November 1,
2. Optimum moisture content
65% for corn
70% for sorghum
3. Chop fine (1/4 1/2 inch).
4. Fill as rapidly as possible.
5. Pack thoroughly from the beginning,
layer by layer.
6. Push the silage to as great a depth as possible -
Helps pack the silage
Less surface exposed in relation to the volume
Particularly important with silage piled in the
open without walls
7. If possible, cover with plastic weighted with tires.
More important with small silos where silage is
not piled at as great a depth and is not,
packed as tightly as with large bunker
8. When removing silage from a silo, spoilage and shrink
will be reduced by maintaining a smooth surface on the
face of the pile, and avoiding loosening up the silage
that is not removed.
FEEDING CORN AND SORGHUM SILAGE
Generally, the percentage of moisture is lower, the per-
centage of grain is higher, and the percentage of total digestible
nutrients (TDN) is higher in corn than in sorghum silage. In the
three years, 1979-1981, corn silage at the Agricultural Research
Center, Jay, produced only 37% as much green weight per acre but
had 45% as much dry matter (moisture-free weight) and 77% as much
grain per acre as sorghum silage. For wintering brood cows, the
lower nutrient content of the sorghum silage does not create as
much of a problem as with calves and yearling cattle, because the
cows are usually able to consume enough of the sorghum silage to
meet their need for TDN. However, with calves being grown or
backgrounded, grain must be added to sorghum silage to provide the
TDN needed for satisfactory gains. To make sorghum silage
comparable to corn silage for calves:
1700 Ib sorghum silage
300 Ib grain
is equivalent to
2000 lb corn silage
Both silages need to be supplemented with protein, minerals,
and vitamin A.
1. Winterina brood cows and calves
a. 1000 lb pregnant cow
Lh 40% protein sup./day
b. 1000 lb cow nursing calf
Lb 40% protein sup./day
2. Growing 400 Ib steer cal, 1.5 lb gain/day
Lb silage/day 20
Lb shelled corn/day 2.0
Lb 40% protein sup./day 1.5
Total per day, lb. 23.5
Growing 600 Ib steer calf, 1.5 lb gain/day
Lb silage/day 30.0
Lb shelled corn/day 3.0
Lb 40% protein sup./day 1.5
Total per day 34.5
In the calf growing examples, it is assumed that the corn and
sorghum silages are high quality, with a moisture content of 65%
for the corn silage and 70% for the sorghum silage. With more
realistic assumptions of somewhat lower quality and perhaps higher
moisture content of the silages the following general recommenda-
tions are suggested:
(1) With calves weighing 400 to 600 lb, supplement corn
silage with shelled corn at the rate of 0.5 to 1.0% of
body weight daily (2 to 4 lb corn daily to a 400 lb
calf), plus the silage and protein supplement.
(2) With calves weighing 400 to 600 lb, supplement sorghum
silage with shelled corn at the rate of at least 1.5% of
body weight per head daily (6 lb corn daily to a 400 Ib
calf) plus silage and protein supplement.
(3) Sorghum grain (milo) may be substituted for shelled corn,
using 10-15% more sorghum grain than shelled corn.
(4) Sorahum rain must always be ground or rolled for satis-
factory grain utilization. However, whole shelled corn
will be utilized efficiently if: (1) the amount fed does
not exceed 5 lb per head daily, or (2) the roughage level
in the total ration does not exceed. 15%. With qood
quality silage, the example rations would meet these
Finally, in estimating quantity of silage (corn or sorghun)
in a bunker or trench silo, the rule of thumb is 35 lb per cubic
foot of well packed silage.
Small Grain and Alfalfa Silage
M. E. McCullough
Georgia Station, Experiment, GA 30212
In the southeastern United States, we frequently need a substitute
for corn silage. Our need is that of beating hot, dry summer weather -
and not corn silage. At the Georgia Station, we have harvested both
spring and summer silages for 28 years. Over that period, we have
harvested 5 or 6 truly great corn crops, 6 or 8 failures, and the rest
somewhere in between. During the same 28 years, we have had only one
failure with small grains for silage.
Harvested and ensiled correctly, small grain silages can be as
useful as a forage source as corn silage. They can have a dry matter
digestibility of 65%, compared to good corn at 68-70%.
We did one piece of research with wheat silage where we harvested
the wheat at three stages of maturity (heading, milk, and dough stage),
and fed each silage at three silage to grain ratios 100:0, 30:70 and
50:50. The major results are in the table.
D.M. Daily intake (gm/kg)W73
Stage of dig. of Silage
harvest silage alone 30:70 50:50
Heading 64 118 166 176
Milk 58 108 145 153
Dough 58 104 147 156
The important points are:
a) To produce a silage with a dry matter digestibility near
65% (the quality required by dairy cows and growing cattle),
the small grain should be harvested at the late boot to
early heading stage.
b) Quality lost through delayed harvest cannot be entirely
recovered by grain feeding.
The late cut silages never permitted as good an intake as the early
cut silage at any ratio of silage to grain feeding. Feeding 50% of the
total ration as grain with the two late cut silages did not result in
as good intakes as the early cut silage with 35% of the ration as grain.
The data point out the major factor in using small grains for silage.
Harvest it at the late boot to early heading stage and do an excellent
job of ensiling.
In my judgment, alfalfa silage should generally be looked upon as a
source of protein and not energy. For this reason, its harvest and
storage should be guided by those practices which best preserve protein.
Since the protein content of alfalfa declines from the time it begins
each new growth, the proper stage of harvest is as early as the plant can
be cut without damage to the plant, and with a yield large enough to fool
with. This is somewhere about the early bloom stage.
Since the major source of protein in legumes is the leaf material,
every emphasis should be on harvesting and preserving maximum leaf material.
This starts with the use of the proper machinery to cut and condition
the alfalfa for maximum wilting rate. Only that amount of alfalfa that
can be ensiled the same day should be cut each morning. Never let the
moon shine on wilting alfalfa. All we want to do is reduce the dry
matter to 30-35% so the seepage is minimized and the sugars are concen-
trated for quick fermentation. Alfalfa is one silage that should always
be ensiled with a good aid to fermentation (additive). We have had
excellent alfalfa silage stored in horizontal silos using a minimum of
wilting and a good additive. The large amount of dry, hot silage I see
each year indicates that most wilting is being overdone.
With both small grain and alfalfa silages, one point cannot be
over-emphasized. When these crops are ready for harvest, they must take
first preference in farm work. You have only a very few days in which
to harvest these crops at.their optimum stage of maturity.
Chemical-Assisted Drying and Fall Grazing of
'Florida 77' Alfalfa
E. J. Golding
Agricultural Research and Education Center
'Florida 77' alfalfa (Medicago sativa L.) is a forage crop
which shows much promise for north Florida. It has the potential
to produce large quantities of high-quality hay, and also may
prove useful for fall grazing, since it does not go dormant
during the cool season of the year. This paper presents partial
results of studies undertaken to investigate 1) the effects of
maturity, raking and the selective application of a commercial
drying agent ('Conservit 11') to alfalfa stems during cutting on
the quality of alfalfa hay; and 2) the effects of fall grazing
and fertilization on the dry-matter (DM) yield and persistence of
a stand of 'Florida 77' alfalfa.
Chemical-Assisted Drying of Alfalfa Hay
The longer that cut alfalfa hay lies in the field to dry,
the lower its quality is likely to be. If a drying agent were
applied only to alfalfa stems during cutting, so that stems dried
as quickly as do leaves, then alfalfa hay might be ready for
baling in a shorter time. Also, leaf shatter might be reduced
and hay quality enhanced, since leaves might not be overdry in
comparison to stems at baling. To study these possibilities,
'Conservit 11' drying agent was applied during cutting at rates
of 0, 5 or 10 pounds per ton of 20%-moisture hay to stems of
4.5-or 6-week 'Florida 77' alfalfa regrowth. Half the hay was
raked into windows prior to baling, while the other half was
baled directly from the cut swaths. The 12 resultant hays then
were fed to sheep to determine hay quality (digestible DM intake,
or DM digestibility multiplied by DM intake).
Harvest practices used in this experiment and difficulty in
determining hay DM in the field did not allow for fair evaluation
of all hays in terms of required drying time. However, 6-week,
non-raked hays which received the 5- or 10-pound levels of drying
agent were sufficiently dry for baling at 26 to 27 hours after
cutting. Similar raked hays probably could be baled after about
the same amount of time, if the proper operational schedule were
followed. Six-week control hays (no drying agent applied) were
baled at 15% moisture after 48 hrs., while 4.5-week controls were
baled after 48 hrs. at 20% moisture. Hays which received either
5- or 10-pound levels of drying agent at 4.5 weeks of regrowth
dried in a manner similar to that of the 6-week controls. Mold-
ing was not seen in any of the hays.
Table 1 reports results for DM intake, DM digestibility and
digestible DM intake (quality) by sheep as affected by 'Conservit
11' application, maturity and raking. Application of 'Conservit
11' affected neither DM intake (P>.33), DM digestibility (P>.15)
nor hay quality (P>.44). Thus, the hypothesis that selective
application of a drying agent to the stems of 'Florida 77'
alfalfa might increase the quality of alfalfa hay appears false.
Still, this hypothesis might prove true if 'Conservit 11' could
be used to increase the drying rate of alfalfa hay, such that it
could be cut and baled before an impending period of bad weather.
TABLE 1. EFFECTS OF DRYING AGENT, MATURITY AND RAKING ON DM
INTAKE, DM DIGESTIBILITY AND QUALITY OF 'FLORIDA 77'
Drying Agent Maturity Raking
Item 0a 5 10 4.5b 6 + -
DM Intakec 63 61 59 65 57 58d 64e
DM Digestibility, % 63.2 65.5 67.0 68.0 62.4g 64.0 66.3
Digestible DM intake 40 40 40 45h 36i 38d 43e
pounds of drying agent per ton of 20%-moisture hay. bWeeks of
regrowth. cg/kg 75/day. d'eWithin raking, in the same row,
P<.05. 'gWithin maturity, in the same row, P<.01. hi Within
maturity, in the same row, P = .07.
The difference in DM intake due to maturity was not large
enough to be considered significant (P>.32). However, DM
digestibility was higher (P<.01) for the 4.5-week-regrowth hay,
and the probability of quality being higher for the 4.5-week hay
was 93%. This supports the idea of using a drying agent if it
would aid in the harvesting of hay before the arrival of impend-
ing bad weather, since the maturity difference between hays was
only 11 days.
Raking did not have a significant effect (P>.21) on DM
digestibility. However, DM intake and hay quality were higher
(P<.05) when hay was not raked into windows. Thus, raking of
'Florida 77' alfalfa hay apparently should require a management
decision, in which such factors as hay price, and fuel and
machinery costs should be considered.
Fall Grazing of 'Florida 77' Alfalfa
Since 'Florida 77' alfalfa does not go dormant during cool
weather, the possibility exists that it could furnish much-
needed, high-quality grazing for cattle during the fall season.
First, however, the effects of fall grazing on the DM yield and
persistence of the alfalfa stand must be investigated. To begin
to accomplish this, the first year of a mob-grazing study which
involves days of rest between grazings (28 or 42 days), grazing
intensity (2 calves grazing for 1, 2 or 3 days), and fertiliz
ation practice (none or 150 pounds per acre of 0-0-60 after
initial fall grazing) was conducted during 84 days at Chipley,
Florida, from late September, 1982, to early January, 1983. The
12 treatments, plus a non-grazed, non-fertilized control, were
studied on 39, one-sixth acre pastures. Only results from the
final pasture sampling for DM yield, in late December 1982, and
early January, 1983; and the persistence sampling, in early
April, 1983, will be presented here.
Table 2 shows that, at the final-grazing sampling, pastures
grazed every 28 days for either two (P<.05) or three (P<.01)
days, as well as those grazed every 42 days for three days
(P<.05), had lower DM yields than control pastures.
YIELDS OF DM FROM FALL GRAZED 'FLORIDA 77' ALFALFA
PASTURES FOR FINAL-GRAZING AND PERSISTENCE SAMPLINGS.
Treatment Final-Grazing Persistence
28a:1b :c 1424 2129f
28:1:+ 1463 2300f
28:2:- 1309e 2111,
28:2:+ 1303 2056f
28:3:- 967 1986,
28:3:+ 1045 2044
42:1:- 1650 2141f
42:1:+ 1432 2240f
42:2:- 1558 1995.
42:2:+ 1520 2210
42:3:- 1346e 2217f
42:3:+ 1348 2163
Control 1587 2549
aDays of rest betw
after initial graze
from control (P<.
bNumber of days that two calves
cWith (+) or without (-) 150 lbs/a of 0-0-60
sing. dNo grazing, no fertilizer. eDifferent
05), within column. fDifferent from control
(P<.01), within column.
Thus, over 84 days, these treatments lowered the amount of DM
available for the final grazing. Table 3 indicates that grazing
every 42 days should result in more 'Florida 77' alfalfa DM being
available for the final grazing (P<.01), as should grazing for
either one or two days (P<.01). Application of 150 lbs/a of
0-0-60 after initial grazing apparently had no effect (P>.62) on
final-grazing DM availability.
Table 2 also shows that all grazing treatments lowered
(P<.01) persistence, when compared to the control. This may
prove not too critical, as growth on control pastures at time of
persistence sampling appeared more rank and stemmy than did
growth on grazed pastures. Thus, higher (P<.01) persistence on
control pastures may not translate into higher yields of crude
protein and/or digestible DM. Further analyses of the samples
will elucidate this question.
TABLE 3. EFFECTS OF DAYS OF REST, GRAZING INTENSITY AND FERTILI-
ZER ON DM YIELDS OF FALL-GRAZED 'FLORIDA 77' ALFALFA
PASTURES FOR FINAL-GRAZING AND PERSISTENCE SAMPLINGS.
Days of Rest Grazing Intensity Fertilizer
Sampling 28a 42 ib 2 3 +c
Final-grazing 1252d 1475e 1492d 1422d 1176e 1375 1352
Persistence 2104 2161 2202 2093 2102 2096 2169
aBetween grazing. bNumber of days that two calves grazed
pasture. cWith (+) or without (-) 150 lbs/A of 0-0-60 after
initial grazing. deWithin variable and within row, numbers with
different superscripts differ (P<.01).
Table 3 shows that neither days of rest between grazings (P>.43),
grazing intensity (P>.40) nor application of 0-0-60 (P>.32)
appeared to have any effects on persistence of fall-grazed
'Florida 77' alfalfa.
Taken together, these first-year results from final-grazing
and persistence samplings of fall-grazed, 'Florida 77' alfalfa
pastures indicate that the most-favorable way for a rancher to
undertake such grazing would be every 42 days, for two days, with
no application of 0-0-60. This apparently would not affect
persistence relative to other studied grazing methods (P>.77),
and would not lower (P>.80) DM availability for the season's
final grazing. Also, of the feasible fall-grazing methods
indicated by this study, this method would result in the highest
possible number of animal-days/a (72), over the 84-day grazing
season. However, it must be remembered that these results are
from the first year of the study. Results from future years may
change the picture totally.