Warm Season Perennial Grasses for the Southern
Great Plains
Will C. Cradduck – Texas Tech
University
Introduction.
Grasses that are productive, well adapted, and tested on the southern Great Plains will be in greater demand in the near
future. The decreasing availability of
water from the Ogalalla aquifer will require producers to look for options that
are not as dependent on irrigation.
Forage-based livestock production could be an important option to
traditional row crops. Forages other than native grasses will be needed to
expand forage availability throughout the year and to allow increased forage
production with increased inputs.
Identifying such grasses would allow producers more flexibility when
designing grazing systems, and would allow animals to graze a greater percentage
of the year, thus, reducing dependence on supplemental feed.
Rationale.
This study will determine effects
of different species and cultivars on persistence, quality, mineral
concentration, and biomass production of selected warm season perennial
grasses. Please see the end of this
summary for a plot map and list of grass species. Knowledge of warm season perennial grasses
that can reliably produce forage in the summer months on the southern Great Plains with limited irrigation will be important to
livestock producers. Quality and mineral content of these forages will also
be important information so that producers can identify possible deficiencies,
and supplement the forage or the animal to prevent loss of production in the
grazing animal.
Grasses
included in this study are, for the most part, known to exist on the southern Great Plains but were a minor part of the historic
vegetation. Historically, the southern Great Plains was primarily buffalograss and blue grama, with
taller grasses like the ones included in this study occuring in lower areas
along creeks, draws, and other waterways.
They are large plants, with very deep rooting systems. Rooting depth on the southern Great Plains is often limited by the presence of a petrocalcic
(caliche) horizon in the lower part of the soil profile, usually below 100 cm. An important part of this study is to see if
these generally deep-rooted grasses are limited in production or persistence by
this limited rooting depth. If these grasses
can be succesfully grown on the southern High Plains under limited irrigation,
they may have increased potential for biomass production over the native
grasses. The deep rooting habit of these
grasses may be important during periods of drought. Producers could sacrifice some production and
allow these grasses to survive the drought on moisture deep in the soil
profile, and then maximize production with supplemental irrigation during
periods of normal rainfall.
Methods.
Ten warm
season perennial grass species were planted near Lubbock, TX
in spring 2002, and reseeded in spring 2003.
Plots are fertilized in spring and mid-summer with 60 lbs N/acre at each
application. Irrigation is limited to 12
inches annually, applied from late spring to late summer through sub-surface
drip. Plots will be harvested as for hay
through the summer according to growth stage and individual cutting height and
frequency recommendations. Persistence
and biomass production will be monitored from hay cutting. Forage mineral concentration and forage
quality indicators will also be determined from each hay cutting.
Results.
This study
took two years to establish, and we have learned valuable lessons about the
establishment of these warm season perennial grasses. Probably the most important lesson learned is
that these grasses are slow and difficult to establish. Two notable exceptions are sorghum almum and
johnsongrass. These two grasses established
easily and completely in 2002. Both did
extremely well in 2003, but sorghum almum has not come back well in the spring
of 2004. Kleingrass established fairly
well in 2002, as did switchgrass, though not as well as kleingrass. Caucasian bluestem and big bluestem had some
establishment in 2002, but were below 50%.
Caucasian bluestem was slower in 2002, but surpassed big bluestem in
2003. WW-B. Dahl bluestem did not
establish well in 2002, but has surpassed big bluestem and was similar to Caucasian
bluestem for 2003. Eastern gamagrass
established very little in 2002 and required reseeding for 2003, but I would
now consider it well established for
2004. Little bluestem has not
established well so far, and might only be viable as a portion of a grass mix
rather than a monoculture. For 2004, the
plots have good stands, with the exception of little bluestem and sorghum almum.
Persistence
of these grasses is an important aspect of this experiment. The preliminary data below shows that sorghum
almum is not persisting, and we have also lost a few little bluestem plants. The % stand counts for eastern gamagrass show there to be few plants
per plot, but based on the large size of mature plants, this is not a
problem. Also, the graph shows increases
in stand counts of eastern gamagrass from last summer to this spring. This is not due to more seeds sprouting, but
instead an increase in crown size due to tillering. This is also true for big bluestem.
There are a few noticeable
differences in when these grasses break dormancy in the spring, as well as when
they reach a first haycut stage (50% panicle emergence). Kleingrass and eastern gamagrass were the
first to break dormancy, and also first to reach a haycut stage. The kleingrass and eastern gamagrass reached
haycut stage on May 25, 2004. The canopy
height graph below demonstrates the difference in spring productivity for these
grasses.
This is our first year to get any biomass production and
stand count data, and we are just beginning to get that information. Plots are harvested for biomass as they reach
50% panicle emergence. For the first
haycut on May 25, 2004, kleingrass yielded 3234 lbs/acre, Iuka eastern
gamagrass yielded 5186 lbs/acre, and Pete eastern gamagrass yielded 6208
lbs/acre.
Conclusion.
Even though
establishment may be somewhat prolonged, these grasses show promise as viable
forage species on the southern Great Plains. Several of these grasses show promise of
exceptionally high biomass production per acre.
More data is needed on these grasses, as well as work on easier
establishment.
Warm Season Perennial Grasses Plot Map
N
W E
S
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10
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3
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9
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6
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7
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10
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9
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10
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1.
Sorghum almum; Sorghum almum
2.
Johnsongrass; Sorghum halipense
3.
Kleingrass; Panicum coloratum; Selection 75
4.
Switchgrass; Panicum virgatum; Blackwell
5.
Eastern gamagrass; Tripsacum dactyloides; Iuka
6.
Eastern gamagrass; Tripsacum dactyloides; Pete
7.
Big Bluestem; Andropogon gerardii; Kaw
8.
Little bluestem; Shizachyrium scoparium; Cimmaron
9.
WW-B. Dahl old world bluestem; Bothriochloa bladhii
10. Caucasian
old world bluestem, Bothriochloa caucasia