Managing Drought-Stressed Pastures
Recently, a panel of range and pasture experts offered four steps they're advising pasture managers to implement this spring.
1. Manage grazing - conservatively
Grasses stressed by months or years of drought, and, in many cases, overgrazing, will have weakened root systems and less vigor. In drought, grasses produced fewer buds and tillers. Some plants may have died, thinning a stand.
"Don't expect drought-stressed pastures to return to pre-drought condition overnight," says Dr. Jerry Volesky, Extension range and forage specialist at North Platte, Neb. "Even with rain, there may not be an adequate root system there to support the production of new plants, although existing plants will likely increase in vigor."
On native pastures, some growing season rest is critical to recovery. In the Northern Plains, even a few weeks delay in turnout will help, Volesky says. In the Southwest, the ideal is rest for a full growing season, says Dr. Wayne Hanselka, Extension range specialist at Corpus Christi, Texas.
"Err on the side of caution," Hanselka advises. "Restock on the basis of production. Stock lightly and build up slowly. The drought is not over until sub-soil moisture is replenished."
Improved grasses in more humid climates are usually less sensitive to close grazing than natives, says Dr. Don Ball, Extension forage specialist at Auburn University in Alabama. "But if you have plants that were severely stressed already, give them a break. They will need some TLC."
2. Manage weeds
Weakened grass plants, thin stands and bare ground, combined with moisture, make a recipe for robust germination of broadleaf weeds, especially annuals. Usually, the weed seed is already there, but a new supply may have arrived in purchased hay. šPerennial weeds, especially noxious invasives, also benefit from drought and overgrazing, Volesky says. With adequate moisture, patches of leafy spurge, thistles and other weeds may expand and new patches may establish. It usually takes more than a single moist year for native perennial grasses to improve in density, says Dr. Patricia Johnson, a range science researcher for South Dakota State University, stationed in Rapid City. So weeds may have a long period of opportunity, and many weed seeds remain viable for years. "Be careful where you feed, and remember to visit those feeding sites in years to come, to watch for imported weeds," she says.
Follow recommendations for weed control, the experts say. Identify weeds, choose appropriate herbicides, and time applications to best accomplish the goal. Prescriptions will vary by locale. "Grazing may help with weed control in some situations, but not all," Hanselka says. Herbicides with soil residual activity may help with timing.
At appropriate labeled rates, herbicides with residual activity control weeds that have emerged, and they remain active in the soil to control many that germinate for a period after spraying, explains Dr. Vernon Langston, a field scientist with Dow AgroSciences. Not all pasture herbicides offer residual activity. Some can be applied up to waters edge, and have no grazing restrictions, even for dairy cattle.
Don't spray when it's too dry, Hanselka emphasizes. Herbicides are less effective then, and, for soil protection, even weeds may be preferable to bare ground.
3. Fertilize improved pastures
To help improved grasses, such as bermudagrass, bahiagrass, fescue and orchardgrass, take soil tests and follow the recommendations.
"Proper soil pH and adequate soil nutrients always enhance forage competitiveness, whether you've had a drought or not," Ball says. Pastures with poor fertility and low pH will be particularly slow to recover after a drought.
4. Prepare for the next drought
Most of all, experts advise, plan for the next drought. That's when good management really pays.
"After a drought, it takes five to seven years to recover to a post-drought level, and, on average, we have a drought every three years," Hanselka says. Proper stocking and grazing are critical. Seasonal grazing rotations - not grazing the same pasture at the same time every year - will improve pasture health in drought or normal weather, Volesky says.
Don't set stocking rates by what pastures will carry in good years, Johnson emphasizes. Diversify cow-calf operations to include stocker or yearling numbers you can easily adjust. And, remember, she says, "The harder you graze, the longer it will take the plant community to rebound."
By: The Cattle Site