USING ALFALFA-GRASS
MIXTURES TO MINIMIZE
DEER DAMAGE
M.H. Hall and R.C. Stoudt,
Penn State Extension
Alfalfa is a prime feed source for
both dairy cows and on-domesticat
ed, white-tailed deer in
Pennsylvania. Damage to alfalfa
can be great. Numerous attempts
have been made to deter deer from
feeding on alfalfa and other crops
but they have generally proven
unsatisfactory because of high costs
and/or ineffectiveness. Several
researcherl have reported that deer
prefer alfalfa to forage grasses.
However, the use of alfalfa-grass
mixtures to deter deer from feeding
on forage has been untested.
Study Description
Plots of alfalfa, timothy, orchard
grass, and alfalfa-timothy or
orchardgrass mixtures in 3:1, 2:2,
and 1:3 alfalfa to grass row arrange
ments were established within
areas protected (with fencing) or
unprotected from deer feeding.
Forage from these plots was har
vested three and four times in 1995
and 1996, respectively, and dry mat
ter yield, percentage alfalfa and
grass, and forage quality were
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determined. Economic evaluation of
each treatment was made based on
the value of the harvested forage
and the differential costs associated
with production.
Applied Questions
• To what extent do deer dam
age forages in central
Pennsylvania? Forages protected
from deer feeding averaged 1660
Ib./acre more DM yield than their
unprotected counterparts (Table 1).
The greatest amount of deer feeding
occurred in pure alfalfa and the
least jo pure orchardgrass. Fomge
quality was not affected by deer
grazing. Weeds began to invade the
plots in the second year of the study
and were more severe in the unpro
tected than protected plots. Deer
feeding resulted in average econom
ic loss of $BO and $2B/acre for pure
alfalfa and pure orchardgrass,
respectively.
•Do deer selectively graze
one forage species over anoth
er? Deer selectively grazed alfalfa
out of the alfalfa-grass mixtures and
fed more on plots which contained
timothy than those which contained
orchardgrass. Averaged across all
mixtures, alfalfa made up 35% of
the total yield in the protected but
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Foraging Around, Lancaster Farming, Saturday, October 24, 1998—Page
only 19% in the unprotected mixed
plots. Average yield reductions, as a
result of deer feeding, were 1507
and 1102 lb./acre (excluding weed
yield in 1996) for treatments con
taining timothy and orchardgrass,
respectively (Table 1). Consequently,
the economic losses associated with
deer feeding were greater for mix
tures containing more timothy than
orchardgrass (Table 2).
• In a field where deer gener
ally feed, are particular forage
species mixtures better than
others? In areas unprotected from
deer feeding, pure orchardgrass and
alfalfa-orchardgrass mixtures had
greater total yields than pure alfalfa
(Table 2). Weed infestation in second
year of the study was greatest in
pure alfalfa which had the greatest
deer feeding and least in pure
orchardgrass which had the least
deer feeding in the first year of the
Table 1. Decrease in dry matte&yiftjd associated with deer feeding compared
to no deer feeding on pure alfalfa, pure grass, or alfalfa-grass mixtures
seeded in different row arrangements (mean of two locations for two
years).
Grass
species
Timothy
Timothy
Timothy
Timothy
Orchardgrass
Orchardgrass
Orchardgrass
Orchardgrass
tßeduction in alfalfa and grass yield combined. Weed yield is not included
in total.
study. Forage quality was not affect
ed by deer feeding within the unpro
tected plots but was affected by the
proportion of alfalfa to grass in the
mixture. Alfalfa-orchardgrass mix
tures had greater economic returns
than pure alfalfa but only when
alfalfa was seeded at >50% of the
mixture (Table 2).
Recommendations
Deer feeding can greatly reduce
forage yield. Deer selectively grazed
alfalfa out of alfalfa-grass mixtures
and showed a preference for timothy
over orchardgrass. The use of
orchardgrass alone or in a mixture
with alfalfa reduces deer feeding
and provides the greatest yields.
However, when deer feeding
occured, net economic returns were
greater for alfalfa-orchardgrass mix
tures because of improved quality
compared to pure orchardgrass.
Rows alfalfa:
rows grass alfalfa grass total 1
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Reduced yield
Ib/acre
2392 0 2392
2229 154 2384
1272 926 2198
900 822 1722
0 1230 1230
1732 134 1866
1050 568 1617
698 394 1092
0 435 435
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