VALUE AND USE
SPECIES: Pleuraphis  mutica | Tobosa 



WOOD PRODUCTS VALUE : 
NO-ENTRY


IMPORTANCE TO LIVESTOCK AND WILDLIFE : 
In the southwestern United States tobosa is an important forage
species for cattle and horses.  Although it is a highly productive grass
of southwestern rangelands, it is generally considered to be unpalatable
after maturity as the tough dry stems and leaves have little nutritional
value.  It is palatable to livestock only when it is green and succelent
during the summer months [11,28], at which time it is considered good for
cattle and horses [49].  Grazing is generally restricted to spring
through early fall when its main growth occurs [37,49]. It withstands
grazing very well during the summer at which time up to 60% of its
herbage production may be utilized without injury [11].  During drought
years it is considered a reserve feed by southwestern ranchers [53].
Tobosa has also been cut for hay.  The hay is readily eaten by
cattle if it is cut when green and succelent, and cattle fed on it will
remain in good condition throughout the winter [37].

On bottomland sites where tobosa occurs in almost pure stands it is
capable of producing abundant forage, sometimes several times that of
upland sites.  In Texas, during years of average precipitation,
tobosa yields are normally about 1,000 pounds per acre (892 kg/ha)
[52].  In southern New Mexico yields are normally 1,000 to 1,500 pounds
per acre (892-1338 kg/ha) [37].  Under management plans to remove dead
old growth, these stands can produce considerably larger amounts of
forage.  Early spring burns followed by sufficient moisture have
increased tobosa yields two to three fold in Texas [53].
   
In Texas it has been shown that tobosa may become infested with
ergot (Claviceps cinerea) [13].  Ingested tobosa infested with ergot
can cause a nervous condition in cattle.  The signs of poisoning
include excessive salivation, muscular twitching, staggering gait,
knuckling over the rear fetlock, and frequent urination.  There is
limited literature on this condition and the extent of outbreaks is
unknown.


PALATABILITY : 
Throughout its range, the forage value of tobosa has been under
rated either because cattle prefer upland grama ranges (Bouteloua spp.)
where plants are more nutritious, or because after maturity plants
become coarse and unpalatable [51].  But during late spring to early
fall when plants are green and succulent their forage value is good for
cattle and horses, fair for sheep, and poor for wildlife [11,32,37,46].
This was observed in a New Mexico study where cattle would eat
tobosa only from July to October [32].  After growth has ceased the
stems and leaves become so dry and tough that they retain little value
and are refused by livestock if other feed is available [11].


NUTRITIONAL VALUE : 
The nutritional value of tobosa is highest during late spring to
early fall at which time plants are green and succulent.  At the end of
the growing season the crude protein content of tobosa's current years
growth was found to be 8.4%, while that of the previous years growth was
4.7 % [1], which is considered an unaceptable nutritional level.

Seasonal trends in the chemical composition of tobosa on the
Jornada Experimental Range in New Mexico are as follows [28]:

                                         % acid      % acid  
                               % ether   detergent   detergent 
                  % protein    extract   fiber       lignin      % ash

Mature    July       8.6         1.3       47.2        6.8        8.5
Overripe  August     10.2        2.2       42.0        6.8        9.2
Mature    September  9.2         2.0       43.2        6.8        8.2
Dough     October    7.9         2.0       48.6        8.5        9.9
Dormant   February   4.8         1.2       50.3        9.3        8.6

                  % calcium  % phosphorus  % potasium  % magnesium

Mature    July       .38         .19           1.2         .08
Overripe  August
Mature    September  .39         .16            .28        .07
Dough     October    .36         .12            .75        .07
Dormant   February   .36         .07            .41        .04
  


COVER VALUE : 
NO-ENTRY


VALUE FOR REHABILITATION OF DISTURBED SITES : 
NO-ENTRY


OTHER USES AND VALUES : 
NO-ENTRY


MANAGEMENT CONSIDERATIONS : 
Deferred grazing is considered best for tobosa stands with utilization
occuring in the summer.  In areas where tobosa and black grama
(Bouteloua eripoda) occur in separate stands, it is best to fence large
areas of tobosa into permanent pastures.  This allows cattle to stay on
the tobosa during the summer months when it is most palatable;
black grama can then be grazed during the winter when it is palatable
[11,37,51].  Grazing utilization should not exceed 50% during any one year
[56].

One important characteristic about tobossagrass is its growth from
perennial stems.  With insufficient grazing, large quantities of
standing dead grass accumulate which decreases yields and palatability.
In Texas, it was shown that when this dead material is allowed to
increase, annual new growth will decrease until the yield stabalizes at
about 800 to 1100 pounds per acre (714-981 kg/ha) [5].  Removing old
growth may be done by heavy grazing, burning, or mowing it for hay.
Conservative continuous stocking during the growing season has been the
traditional stocking method on tobosa range.  But recent studies show
that flexible rotation grazing is not only more effective at reducing
this old growth than is continuous stocking, but that heifer live weight
gains per ha ranged 43 to 24 % less under continuous stocking than under
rotation grazing management [1].  Generally tobosa withstands
grazing well and is considered an increaser [37,51].  Studying the
effects of different grazing intensities on tobosa in southern New
Mexico, it has been shown that protected areas tend to stagnate with
plants having the lowest basal area of four grazing intensities, while
in stands that were intermediately grazed plants had the highest basal
area [37].

Fire, which is discussed in more detail in the "Fire Effects" catagory,
is a very effective tool in managing tobosa stands in areas with
sufficient rainfall.  It is the most effective and the least expensive
method of removing old litter.  In Texas decadent stands of tobosa were
made productive and palatable by burning during a wet spring.  Here
cattle normally utilized only 10 % tobosa but following fire this
increased to 66 % [23].  Grazing should take place immediately after
burning so cattle can eat it while it is young and tender [53].  If it
is rested for three to four months after burning it will become coarse
and unpalatable.

Under most circumstances fertilization is not an economical way to
increase tobosa yields.  But ranchers with a limted amount of
tobosa could fertilize in some years to obtain additional summer
forage in order to defer their upland areas for winter-spring grazing.
Areas to be fertilized should have dense stands of tobosa and be
situated so they are likely to receive run off water even during drought
years.  Rates of 60 or 90 pounds of nitrogen per acre plus 0 or 13.1
pounds of phosphorus per acre seem best [24].  Benefits from
fertilization are not carried on to succesive years.

Related categories for Species: Pleuraphis mutica | Tobosa