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Those crunching sounds you hear as you walk through your pasture aren't
spilled potato chips from last nights barbecue. More likely, drought-stressed
grasses are beginning to turn dry and brown.
Drought-stressed pastures are especially susceptible to overgrazing. While
a healthy dryland pasture might produce 1200 lb. of forage per acre in
a normal year, production might be reduced to a few hundred pounds per
acre during a drought. With less growing grass in the field it will take
less time before grazing animals remove more of the plant than it can
afford. Also, grasses are water-stressed and will make little or no regrowth
after grazing.
"The effects of a drought will be felt beyond the current year"
says Dr. John Ortmann, extension range specialist at Colorado State University.
"Plants will go into the winter with fewer reserves. That means there
could be more winter kill and surviving plants will have less vigor next
spring even if the drought breaks," Ortmann said.
If you irrigate your pastures, you could find yourself running out of
water this year.
"Irrigation water won't go as far during a hot, dry year," adds
Ortmann. "There are more losses to evaporation and a bigger deficit
in the soil that must be filled before water is available to the grass."
If you don't have enough water for all your pastures, concentrate on keeping
a few pastures in good condition for grazing. Reduce irrigation and grazing
on the set-aside pastures.
If you cut your grass for hay, you may want to cut earlier during a
drought. Hay should be cut based on the growth stage of the grass, not
based on a calendar date. During drought, many grasses will mature early.
Hay should be cut in the boot stage, which is when the seed head is inside
the stalk. A good way to time a cutting is when the first seed heads start
to emerge in the field. At that time, a majority of the field will be
"in the boot." Later harvests actually can yield less, because
lower leaves are dropping from the plants, which in turn also reduces
forage quality and palatability.
Weed pressures also can increase during drought years. Many weeds, especially
perennials such as Canada thistle, leafy spurge and bindweed, have deep
roots and more access to moisture than pasture grasses. Weeds get an additional
advantage when grasses are grazed and become less competitive. In essence,
grazing contributes to the "farming of weeds," as the plant
community tilts in favor of weed instead of grass production. When those
weeds drop their seeds they will find perfect conditions to establish
in weakened or denuded pastures.
To reduce future weed problems, mow the pasture before weeds produce
seed. For many weeds the best time to mow is near the time of flowering.
The plant has already expended energy to produce the flower stalk and
is less likely to have the resources to send up a second stalk.
Poisonous plants also can be a bigger danger during drought. With little
green grass to graze, animals are more likely to choose lush locoweeds
or larkspurs. Keep animals away from areas with toxic plants to prevent
poisonings.
What is the best way to manage a dryland pasture during a drought? In
many cases, the answer is to keep the animals off it. You will be losing
very little forage, as there isn't much grass out there to graze. And
you'll minimize damage to the grass plants so you will have more forage
next year. If it rains next year, that is.
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