Showers
crossed the state last weekend (6-17-12), but in many cases it was only enough
to settle the dust for a few hours. The dry conditions in our area continue to
challenge farm managers and their ability to keep forages growing and productive.
While we
can’t control rainfall, we can control our livestock and provide forage plants
the opportunity to remain productive during and, maybe more importantly, after drought
conditions. Overgrazing forage plants anytime reduces maximum growth potential,
but in dry conditions overgrazing forage plants really takes a toll. Allowing
livestock to take more than half of the plant’s leaf material quickly starts
reducing root growth. Also, as excessive amounts of leaf material are removed
during hot, dry conditions, soil temperatures generally increase which slows or
stops growth of our cool season forage plants for extended periods of time.
Overgrazing also contributes to evaporation of soil moisture due to lack of
ground shading.
Ed Rayburn, WVU Extension Specialist, said “root growth determines the ability of a plant to
take up nutrients and water. Root growth is determined by the plant’s leaf area
actively photosynthesizing, since the roots depend on energy captured by the
leaves. When energy is in short supply, it is used by plant tissue nearest to
the site of photosynthesis. Therefore, roots receive energy only when more
energy is produced by photosynthesis than is being used by top growth. However,
under drought conditions the lack of water may reduce top growth while
photosynthesis remains active. This results in the accumulation of
carbohydrates at relatively low canopy heights. Forage stands that have growth
retarded by drought can then have a vigorous regrowth once good rain is
received.”
The key to
this process however, is to leave enough plant leaf residual. As Ed stressed,
photosynthesis can continue to provide energy for roots, but only when
sufficient leaf surface is present to gather sunlight. When forage plants are
overgrazed, top growth must come from root reserve energy which leads to weaker
plants.
Another
consideration, to maintain forage plant health, is the amount of rest/regrowth
the plants have had before being grazed again. Turning livestock into paddocks
that have not had sufficient rest will be very stressful to forage plants. Unimproved
fescue and white clover paddocks should be a minimum of 5-8 inches while
orchardgrass and red clover predominant paddocks or improved varieties of
fescue and clover paddocks should probably be a minimum 8-10 inches tall before
allowing livestock to start grazing again. Using hayfields that have
sufficiently regrown, after first cutting hay was made, or feeding hay or grain
would be options to allow pasture plants enough time for adequate rest and
regrowth before grazing resumes.
Most farm
managers find it hard to feed hay or concentrate feeds in the summer while
there is still a little green forage left in some of their pastures, but
protecting the forage plants and allowing adequate leaf material to remain
after a grazing pass will help you grow more forage per acre in the long run.
Changes
should be made in a proactive manner, rather than reactive to minimize negative
effects on forage and livestock production during prolonged periods of reduced
precipitation. Step-in posts and electrified polywire or polytape can be used
to decrease waste by reducing paddock size and also keep livestock from
overgrazing. Closely monitoring livestock’s grazing and moving them in a timely
manner to maintain adequate residual can pay big dividends during dry periods.
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