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of Journal of Agronomy and Crop Science, is available on the Blackwell Synergy
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Conventional sorghum-sudangrass is not widely grown
as a feed for lactating dairy cattle because it has a lower feeding
value and yields less per acre than corn silage. However, recent research
has found that sorghum-sudangrass enhanced with the Brown Mid Rib
(BMR) gene has a feeding value that may equal or exceed corn silage.
High quality BMR sorghum-sudangrass
has many additional potential advantages over corn silage addresses
issues of environmental and economic concern alike:
Soil Erosion:
USDA NRCS rates the soil erosion potential of sorghum-sudangrass
as ½ that of corn. In addition, on-farm research in 2000 showed
that sorghum-sudangrass is adaptable to a wide range of soil types
and re-growth can be managed as a winter cover crop. Thus, rotations
including this high-energy forage crop can significantly reduce
soil loss over a wider range of soil types and slopes. Reduction
of soil loss is key to soil conservation and water quality as large
amounts of phosphorus can be transported off the farm through soil
loss.
Pesticide use:
BMR sorghum-sudangrass can be grown with little or no pesticide
applications. When planted at the correct depth and soil temperature,
its rapid emergence negates the need for herbicides). Insects have
not been found to be an economic problem and also corn rootworms
do not affect it. This considerably reduced the concern of pesticide
movement into surface and ground water. An additional discovery
of great importance for much of New York is that deer prefer to
use sorghum-sudan stands only as a safe place from which they emerge
to eat corn and legumes. Deer damage to sorghum-sudan is minimal
(figure 1).
Nutrient Management: A 3-cut system
for sorghum-sudangrass, unlike corn, allows for additional (summer)
N application. This enables application of nutrients during a less
hydrological sensitive time of year. In addition, splitting N applications
may reduce its losses through leaching, denitrification, and/or
runoff. Furthermore, labor, equipment availability, and soil trafficability
are much less of a constraint during the summer.
Mass Nutrient Balance: Results from
field experiments conducted in Rennselaer County in 2000, showed
that under intensive management (multiple cut system with high N
applications) BMR sorghum-sudangrass contained twice as much protein
as corn silage. Growing high protein feed on the farm could greatly
reduce the need for additional grain purchases such as soybean meal.
Because of its high digestibility, BMR sorghum-sudangrass has the
potential to support a high forage diet. As Tom Tyluki at Cornell
has demonstrated on the McMahon farm, high forage feeding has a
major impact on reducing the amount of grain brought on to the farm
while supporting high milk production. A reduction in grain imports
could greatly improve the mass nutrient balance on NY farms as it
reduced the excessive quantities of phosphorus that are presently
being imported as a component of feed.
Versatility: BMR sorghum-sudangrass
can tolerate a shorter growing season than corn, thus allowing for
more flexibility in planting date. Its harvest window appears to
be larger than corn silage (no milk line to wait for) and because
it does not require a grain for quality, harvest risk can be spread
out over two or three cuts. This allows for better utilization of
labor and equipment on limited resource farms.
Lower Capital Requirement: Sorghum-sudangrass
can be grown using conventional hay forage planting and harvesting
equipment. It doesn’t require the extra capital cost of a separate
line of equipment like corn. Multiple harvests reduce the farm stress
compared to corn where farmers have just one chance to get it right.
Consistent Production: In the extremely
droughty growing season of 1999, BMR sorghum-sudangrass showed greater
yields than corn on most fields in the region. In 2000, there was
record rainfall in spring, which delayed planting and subsequent
harvests. At all planting dates after June 1, plot yields were higher
than corn silage planted the same date. Yields of BMR sorghum-sudangrass
planted on July 15 were higher than the New York State average corn
silage yields in a normal year.
Our objective is to develop an economically, agronomic and environmentally
sound management system for BMR sorghum-sudangrass as a cost competitive replacement
for corn silage in New York. Individual studies look at optimum N and K management,
seeding rates, timing of harvest, postharvest management and seed quality.