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UNIVERSITY OF FLORIDA
INSTITUTE OF FOOD AND AGRICULTURAL SCIENCES
Library ,NESVI, LORIOA 3211
AGRONOMY DEPARTMENT RI 311
OCT 23 1987
Agronomy Research Report AY- 6-12 J2ne 1986
University of Florida
Alfalfa DrJing and Preservatiorn
O. C. Ruelke, H. H. Vanhorn
and R. P. Cromwell1
Alfalfa, Medicago sativa L., is world recognized as being one
of the best forage producing crops known. With the development of
Florida 77 alfalfa, and recommended management practices for its
production, it is possible to produce excellent quality hay.
Florida 77 alfalfa is a variety that is productive and persistent
on well drained soils in Florida which do not have highly
With depressed prices for corn, soybeans, and other grain
crops, and with considerable increases in costs for nitrogen
fertilizer, pesticides, combines, and fuel, farmers are
considering growing alfalfa hay, not only as a source of nutrients
for their livestock, but also as a crop which can be sold. The
problem which limits profits from producing alfalfa for hay is
unfavorable weather conditions at the time of harvesting, causing
difficulty preserving the forage.
A series of experiments at the Agronomy Farm at Gainesville,
and at the Dairy Research Unit near Hague, Florida, have been
conducted under various weather conditions and at various times of
the year dealing with drying and preserving alfalfa hay. The
objectives of the experiments were to evaluate various procedures
using chemical drying agents and preservatives in producing a
better quality hay. Experience has shown that it is necessary to
get the percentage of moisture of alfalfa below 20% in order to
minimize spoilage and or mold of the hay in storage. This becomes
difficult during the humid and rainy conditions in Florida during
1. Professors of Agronomy, Dairy Science, and Associate Professor
of Agricultural Engineering, IFAS, University of Florida,
COLL-EGE OF AGRICULTURE AGRICULTURAL EXPERIMENT STATION COOPERATIVE EXTENSION SERVICE
SCHOOL OF FOREST RESOURCES AND CONSERVATION CENTER FOR TROPICAL AGRICULTURE
The Institute of Food and Agricultural Sciences is an Equal Employment Opportunity Affirmative Action Employer authorized to provide research.
educational information and other services only to individuals and institutions that function without regard to race, color, sex, or national origin.
HAY DRYING CONDITIONS
Drying conditions vary, tremendously throughout the year as
well as throughout each day." Although daylength is longer during
the summer, cloudiness and showers decrease the effective drying
period of days during the summer in Florida. During a typical
summer day, without rain showers, temperatures in the alfalfa
canopy ranged from the 70's at night, to near 100F during the day
and relative humidity ranged from 100% to 40% as shown in Figure
1. The relative.humidity remained at 100% until after 8:00AM
before it dropped to the minimum, and began to rise again soon
after 4:00PM to 100% by midnight. Long periods of high humidity
at night increase rather than decrease the moisture content of the
hay, as do afternoon showers which occur while the hay is drying.
Likewise, high soil moisture near the surface increases the
humidity in the hay and reduces the rate of drying.
SPEEDING UP DRYING OF HAY
Use of a mower-conditioner to cut and condition the hay is
highly recommended where making hay of alfalfa because stems dry
much slower than the leaves. Setting the mower-conditioner to cut
at a higher stubble height will help to reduce contact between the
hay and the moist soil surface, and will allow for air circulation
that will speed up the rate of drying of the hay.
USE OF HAY DRYING AGENTS
In a late spring harvest of alfalfa at Gainesville, it was
found that it took three days to dry the alfalfa to a safe
moisture level for baling if cut with a sickle bar mower. If cut
with a sickle bar mower and sprayed with potassium carbonate, or
if cut with a mower-conditioner and not sprayed, it took two days
to dry to a safe moisture level for baling. If cut with a
mower-conditioner and sprayed with potassium carbonate it was safe
to bale the afternoon of the next day. The time it takes to dry
to a safe level for baling will vary with time of the year, soil
moisture levels, and weather conditions but using a
mower-conditioner and a hay drying agent will reduce the time
required to dry the hay to a safe level for baling and may make it
possible to escape damage from afternoon showers.
Numerous formulations of potassium carbonate and mixtures of
potassium carbonate and sodium carbonate, some with buffers,
wetting agents, and preservative agents added have been evaluated.
When weather conditions were acceptable for making hay, these
drying agents have significantly speeded up the rate of drying of
alfalfa and reduced the time the hay was exposed to rain showers
in the field, when applied as directed.
USE OF PRESERVATIVES
Unfortunately, during humid rainy periods in the summer in
Florida it is not easy to get hay below 20% moisture so that it is
safe to bale and store. Numerous hay preservatives have been
applied at the time of baling alfalfa hay in Florida. One of the
more effective materials tested was a mixture of propionic acid
and acetic acid.
In our most recent experiment conducted at the Dairy Research
Unit, near Hague Florida, a trial was conducted to evaluate making
alfalfa hay in one day by using the drying agent ProDry, (a
mixture of potassium carbonate and sodium carbonate applied early
in the morning at 5 lbs/ton DM in 32 gals. H20/A) with a sprayer
attached to the mower-conditioner at the time of cutting, and
using the hay preservative Field Fresh, (a mixture of propionic
acid and acetic acid applied at 30 Ibs/ton DM in 9 gals. H20/A)
with a sprayer attached to the square baler at the time of baling
late in the first day. Other treatments consisted of using the
same rate of ProDry alone, Field Fresh alone and an untreated
check harvested the second day.
Weather conditions during the period of this experiment were
partly cloudy and humid although afternoon showers did not occur.
Temperatures and percent relative humidity in the alfalfa plant
canopy during the harvest of one and two day hay are shown in
Figure 1. It should be noted that the relative humidity on June
18, 1985, was 100% until 8:00AM and it took until noon before it
dropped to the minimum for the day. By 4:30PM the humidity began
to rise and reached 100% by 10:00PM. Likewise, air temperatures
remained below 800F until 8:00AM and reached 1000F at noon. A
sharp temperature drop occurred after 5:00PM. Weather conditions
the second day of the experiment were similar.
Percent moisture in the alfalfa at cutting time shown in
Figure 2, dropped from 83% at cutting time to 32.5% in the hay
treated with ProDry and Field Fresh one day hay while it was 38.4%
in the untreated check indicating a significant response to the
drying agent. The preservative Field Fresh alone did not reduce
the moisture content significantly from the untreated check in the
one day hay or two day hay.
Bale temperatures in alfalfa hay at various intervals when
one day and two day hay was stored are shown in Figure 3. It can
be noted that both the one day and two day hays treated with the
preservative Field Fresh were significantly cooler and not heat
damaged as much as the untreated check or the hay treated with
only the drying agent ProDry. However, after months of storage
the one day hay which was baled at a higher moisture content did
increase in bale temperature.
Alfalfa hay quality ratings made Sept. 24, 1985, shown in
Table 1, indicated less color loss, less leaf loss and less leaf
detached from stems in the one day hay than in all of the other
treatments. After 3 months in storage there was some musty smell
and occasional mold present in the one day hay.
Drying agents containing potassium carbonate applied to
alfalfa harvested for hay speeded up the rate of drying when
properly applied in the absence of rain showers. The application
of a preservative containing propionic acid at the time of baling
reduced heating in alfalfa that was baled at a moisture level
above 30% resulting in satisfactory preservation.
Preserving alfalfa hay in one day was possible using a drying
agent and a preservative when no rain showers occurred. Although
preserving alfalfa hay in one day could permit a producer to
escape rain damage, or complete loss of his crop, it should be
pointed out that favorable drying conditions must prevail during
hay harvest. Drying agents and preservatives can be used to
assist the producer but are not beneficial during continuous rainy
weather. During periods of drought, drying agents and
preservatives may not be needed. The use of these materials can
benefit the producer if and when needed.
Note: Data in figures and table were taken from the manuscript
published in Soil and Crop Science Society of Florida Proceedings
of the fourty-fifth annual meetings in Lakeland, Florida, October
f 18 19 20
DATES IN JUNE 1985
Fig. 1. Temperatures and RH in the microclimate
two-day hay making in 1985.
during harvest of' one-diiy nnd
OUntreated check ( 2 day hay )
*Pro Dty4 ( 2 day hay )
* Field Fresh+( 2 day hay )
*Pro Dry+Field Fresh (one day hay )
S(In bales In storage)
8 12 4 8 12 4 July July Aug.
PM MN AM AM N PM 1 15 2
19 JUNE, 1985
Fig. 2. Percentage moisture in alfal
two-day hay was harvested and stored.
fa hay at time intervals when one-lday and
*Means at each tihe interval which are followed by the same letter arc not.
significantly different (Duncan's multiple range test, P=.05).
* o S~Of'I~ 4 a a \' z A a4 'ON 2 a n 4 Is to *A
M .~-E-4g4.. I
~ "' J-1
I, L-L .
IEMPRAT TiM 1:UA
b c u
0 Untreated check (2 day hay)
*tPro Dy + (2 day a y)
*Field Fresh + (2 Jjy hay)
SPro Dry + Field FreOa
(one day ay)
QAM room temp
I I I .
30 5 10
Fig. 3. Temperature in alfalfa hay at various intervals when one
two-day hay was stored.
*Means at each date which are followed by the same letter are not
significantly different. (Duncan's multiple range test, P=.05).
Table ALFALFA HAY QUALITY RATINGS MADE 24 SEP. 1985. __
Musty Mold Leaves Leaves
Smell Present Missing [etaLhed
U I d I i l I I I .
+ Ratings from O=minimum, to 10=maximum, are the average of three ohservers'
evaluations of bales selected at random from each treatment.