VALUE AND USE
SPECIES: Yucca glauca | Soapweed Yucca 



WOOD PRODUCTS VALUE : 
NO-ENTRY


IMPORTANCE TO LIVESTOCK AND WILDLIFE : 
Soapweed yucca provides food and cover for a number of species
throughout its wide range.  Wild ungulates such as deer, bighorn sheep,
and bison utilize this species to at least some degree.  Generally, use
by deer is fairly light, although Dusek [16] reported that soapweed yucca
represented up to 20% of winter mule deer diets in portions of
north-central Montana.  Mule deer in this area also consumed smaller
amounts of soapweed yucca during the spring and summer [16].  It has been
used, generally in trace amounts, by bison on many shortgrass plains
sites [31].  Research indicates that soapweed yucca is of greatest
importance to bighorn sheep during late winter and early spring [40].
It is believed to represent an important and highly nutritious food
source for bighorns during times of climatic stress.

Cattle use of soapweed yucca appears to be fairly limited under normal
conditions [18].  However, during drought periods in the Great Plains,
cattle frequently consume flowers and succulent young leaves wherever
available [13].  Soapweed yucca was chopped and fed as emergency silage
to cattle during severe droughts in the early part of the century
[13,45].  Little documentation exists on the specific value of soapweed
yucca to domestic sheep and goats, although the leaves of many yuccas
are readily eaten by goats [45].  The fruits and flowers of most yuccas
are utilized by many small birds and mammals.


PALATABILITY : 
Soapweed yucca appears to be relatively unpalatable to wild ungulates in
most areas.  Leaves become tough, and spiny as they mature.  Younger,
more succulent leaves, are much more palatable.  However, during
droughts, when other more palatable species are lacking, soapweed yucca
may represent preferred forage.  Soapweed yucca can be made palatable to
domestic livestock, for use during drought emergencies, by burning off
the older leaves and chopping the remainder of the plant for use as
silage to be added to supplements such as cottonseed meal [45].  Flowers
of soapweed yucca appear to be highly palatable to cattle [13], and
presumably to most wild ungulates as well.  The fruits of most yuccas
are also palatable to a wide variety of birds and mammals.  The relish
and degree of use shown by livestock and wildlife species for soapweed
yucca is rated as follows [14]:

                       CO       MT       ND       WY
Cattle                fair     fair     fair     fair
Sheep                 poor     fair     poor     fair
Horses                fair     fair     fair     fair
Pronghorn             ----     poor     ----     fair
Bighorn               ----     ----     ----     ----
Elk                   ----     poor     ----     fair
Mt. goat              ----     ----     ----     ----
Mule deer             ----     good     fair     ----
White-tailed deer     ----     ----     ----     good
Small mammals         ----     poor     ----     poor
Small nongame birds   ----     poor     ----     poor
Upland game birds     ----     poor     ----     poor
Waterfowl             ----     ----     ----     ----


NUTRITIONAL VALUE : 
Soapweed yucca is rated as "poor" in overall energy and protein value
[14].  The nutritional value of soapweed yucca varies seasonally as
follows [6,20]:

                % composition
Date    moisture    carotene    ash    crude    crude     crude
                                       fat      protein   fiber
Jan.18    60.10      27.60      1.59   1.13     4.78      14.81
May 16    55.68      22.10      1.57   1.28     3.79      15.97
June27    64.71      18.04      1.87    .73     3.93      14.62
Oct 22    61.42      43.48      1.49   1.24     3.56      14.67

         N-free extract    Ca     P      Fe       Mn
Jan.18   17.59            .33    .100   40.76    23.20
May 16   21.53            .43    .070   67.31    16.54
June27   14.14            .31    .117   32.82     7.84
Oct 22   17.62            .28    .077   47.11    13.34

                average %
        crude fiber     ash     protein
leaf       42.3         4.86     5.57


COVER VALUE : 
Soapweed yucca provides good cover for a number of smaller birds and
mammals.  Studies indicate that soapweed yucca serves as good hiding
cover for sharp-tailed grouse broods in North Dakota grasslands [22].
Scaled quail in southeastern New Mexico often incorporate soapweed yucca
leaves in their nests which are frequently situated at the base of the
plant [12].  Soapweed yucca provides the following environmental
protection during one or more seasons for wildlife species in a number
of western states [14]:

                     CO       MT       ND       WY
Pronghorn           ----     poor     ----     fair
Bighorn             ----     ----     ----     ----
Elk                 ----     ----     ----     poor
Mt. goat            ----     ----     ----     ----
Mule deer           ----     poor     fair     poor
White-tailed deer   ----     ----     ----     poor
Small mammals       ----     fair     ----     poor
Small nongame birds ----     fair     ----     poor
Upland game birds   ----     poor     ----     poor
Waterfowl           ----     ----     ----     poor


VALUE FOR REHABILITATION OF DISTURBED SITES : 
Soapweed yucca is rated as having low value for short-term
rehabilitation, and low to moderate value for use in long-term
rehabilitation [14].  Plants may be transplanted or grown from seed.
However, seedlings should be mulched in areas subject to winter frost
[1].  Researchers note that soapweed yucca can be somewhat difficult to
propagate [45].


OTHER USES AND VALUES : 
Many Native Americans historically used soapweed yucca for a variety of
purposes.  The saponin-rich roots were pulped to produce soap, thus
giving this species its common name [47].  Fibers obtained from the
leaves were fashioned into baskets, sandals, mats, and ropes [29].

During the early part of this century, soapweed yucca fiber was tested
as a jute substitute in burlap products or cordage.  High tensile
strength (44.7 km), and clean, lustrous appearance made it well-suited
for these uses [5,6].  During World War I, soapweed yucca was used to
produce approximately 80 million pounds of fiber for bags and burlap
[6].  This species was also used to make paper for the United States
Navy during World War II [6,45].

Soapweed yucca is frequently planted as an ornamental [1].


MANAGEMENT CONSIDERATIONS : 
Chemical control:  Soapweed yucca is resistant to the effects of
herbicides.  It is most susceptible during the bud stage, but only poor
to fair control has been achieved [48].

Mechanical removal:  A number of experiments have focused on mechanical
removal or control of soapweed yucca.  Researchers found that recovery
in the number of leafheads is generally not achieved until the third
year after treatment, although in some cases, recovery can occur within
3 months to 1 year.  Recovery in the size (weight) of leafheads is
generally much slower and requires 5 1/2 to 6 3/4 years [45].
Occasionally 2 or 3 new plants grow from each original plant [6].

Evidence suggests that season of treatment and weather conditions do not
significantly influence the recovery of soapweed yucca although recovery
may be slightly slower if plants are damaged late in the year.  Some
plants which had been cut at the soil surface produced inflorescences
within only 23 to 36 months.  Even successive removal or damage has
failed to kill soapweed yucca.  This resilient plant has continued to
sprout for 3 years or more after deep seasonal plowing [45].

Productivity:  Webber [45] reported average soapweed yucca yields of 0.2
to 0.8 ton per acre.  Soapweed yucca is known to decrease in response to
cattle grazing in parts of the Great Plains.

Related categories for Species: Yucca glauca | Soapweed Yucca