Agriculture Reference
In-Depth Information
shorter-season wheat cultivars might offer the
opportunity to produce as many as four crops in
2 years, especially in areas with relatively long
growing seasons and readily available irrigation
(Edwards et al., 2005).
Several areas of the dual-purpose wheat pro-
duction system need attention in future research
efforts. Crop simulation models that can effec-
tively and accurately predict fall forage produc-
tion by winter wheat are needed to improve the
decision-making process for cattle stocking
density on wheat pastures. If properly modifi ed
and calibrated, such models would also prove
useful in determining forage regrowth during
grazing and if adjustments to cattle stocking
density or feed supplementation are prudent.
Similarly, a model that effectively and accurately
predicts wheat phenology in a dual-purpose
production system would be useful in predicting
fi rst hollow stem and optimal timing of grazing
termination in wheat pastures. Elucidation of the
genetic linkage between vernalization require-
ment in winter wheat and timing of fi rst hollow
stem would be an essential component in devel-
opment of such a model. Finally, development of
wheat cultivars with increased daily biomass pro-
duction through greater radiation-use effi ciency
and/or increased water-use effi ciency would
likely reduce the yield penalty associated with
grazing wheat.
Many of the current efforts directed toward
cellulose-based biofuel feedstock production
could perhaps use the dual-use wheat production
system as a model for future research needs.
Switchgrass (
Panicum virgatum
L.), for example,
is a potential cellulose-based biofuel feedstock
that might provide opportunity for both livestock
and feedstock production opportunities within
the same cropping season. Critical factors related
to crop establishment, fertilization, fertilization
timing, and grazing termination that have been
well established for the dual-purpose wheat enter-
prise could likely offer guidelines for initial dual-
use recommendations, and research methodologies
and approaches could be used in developing pro-
tocols for dual-use biofuel feedstock production
research.
Future research in no-till seeding systems that
will allow sowing of wheat into heavy maize
residue immediately following maize harvest
would likely increase yield and acreage in some
areas of the Midwest. In areas dominated by
monocrop wheat such as the Great Plains,
increased infrastructure and improved informa-
tion on rotational crops such as canola (
Brassica
napus
L.), grain sorghum, and sunfl ower (
Helian-
thus annuus
L.) will likely result in increased
adoption of conservation and no-till programs in
this region. Conventional, and perhaps trans-
genic, breeding efforts that will reduce the inci-
dence and severity of diseases worsened by
continuous no-till wheat production, such as
those caused by foliar, root, and crown infections,
will also likely result in increased adoption of
no-till.
There has also been some debate about the
suitability of no-till in forage-only or dual-purpose
wheat systems. Krenzer et al. (1989) observed as
much as a 16% increase in soil bulk density and
a 270% increase in soil strength from cattle traffi c
in a dual-purpose no-till production system. This
compaction was, however, restricted to the top
12 cm in silt loam soil and the top 20 cm in sandy
soil. More work is needed to evaluate the effect
that compaction has on subsequent forage and
grain yield. Likewise, more research is needed to
investigate the extent of alleviation of compaction
through natural methods, such as freezing and
thawing, or through use of rotational crops with
tap roots such as winter canola.
Finally, advances in stress tolerance of wheat
would likely allow reclamation of production in
more marginal production areas that have been
lost due to abiotic stress factors. Advances in our
understanding of mechanisms governing salt
tolerance and tolerance of low or high pH would
allow for production in areas that were once
highly productive but have since been abandoned
or diverted to more tolerant crop species. Toler-
ance to moisture stress, whether it be too much
moisture due to waterlogged soils or not enough
moisture due to drought, would signifi cantly
increase the wheat production potential in many
areas of the world.
