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Tips and options for drought stressed pastures

cow grazing in drought stressed pasture
Cow grazing in drought stressed field. Photo credit: Mercedes Moffett
By: Craig Sheaffer, Extension forage specialist, and David Nicolai, Troy Salzer, Mercedes Moffett, and Katherine Hagen, Extension Educators

Drought has parched many cool-season grass and legume pastures this summer, and in some regions drought has continued into the fall. The drought has affected pasture productivity, plant health, and livestock stocking rate. Here are some tips and options to consider for management of pastures to provide forage for livestock and to insure long term productivity.
  1. Avoid overgrazing. Do not graze below a 4-inch height. Cool season grasses and legumes become dormant during drought. They will likely regrow upon resumption of normal rainfall if not subject to extra stress. During dormancy, the leaves and stems stop growing but the growing points and crowns are still alive. Overgrazing, that removes all leaves and stems can weaken plants and lead to stand loss and weed invasion. Perennial ryegrass, orchardgrass, and timothy that store energy in stem bases are especially susceptible to combined stress of overgrazing and drought, while alfalfa, smooth brome, quackgrass, and reed canarygrass are more tolerant. Shallow rooted species like Kentucky bluegrass and red clover are also damaged by overgrazing.
  2. Reduce stocking rates. If there is inadequate forage available, livestock should be removed from pastures to a dry lot or sacrifice paddock and fed hay. Hay quality should be assessed to determine if it meets the nutritional needs of the livestock. For hay sampling procedures and recommended analysis see the U of M Extension's page on forage testing and the Hay Analysis Guide from UW Extension.
  3. Avoid the temptation of returning to droughted pastures that have regrown following a small amount of rain. It takes 4-6 inches of water to produce a ton of cool season grass or alfalfa forage. Smaller amounts of rainfall may stimulate regrowth but grazing of tall growing grasses should be delayed until 8-10 inch of regrowth. Shorter growing grass like Kentucky bluegrass and red top can be grazed at a 4-inch height. While grazing regrowth before it reaches these minimum heights may provide forage, it can weaken plants and reduce the long-term productivity of the pasture. For alfalfa-grass or red clover-grass mixtures, grazing before these legumes reach a bud stage will reduce their persistence.
  4. Watch out for weeds. Some weeds may grow when grasses and legumes become dormant, and weeds will be grazed if they are the only available forage. In addition to low nutritive value, some weeds like lambsquarters and pigweed are accumulators of nitrate which can be toxic when consumed in large quantities. Another problem weed in woodlands is white snakeroot, which contains a toxic oil, tremetol.
  5. Provide clean water. Livestock normally obtain some water from consuming moist pasture, and switching to dry hay will necessitate greater water availability especially if air temperatures are warm.

Options:

  1. Be proactive and identify sources of hay to meet short- and long-term forage needs. Hay should be purchased to meet the nutritional needs of your livestock and be of sufficient quantity to last till spring pastures are available. For example, for a 1200 lb. cow consuming about 2% of its BW, 24 lb. of hay will be required per day and about 2.5 ton will be required to last from October till May when new pasture is available. Test hay (see above) to determine if it meets nutritional needs of livestock and inspect for anti- quality factors such as mold and weed contamination. Factor in potential losses in storage and feeding can be found by consulting the Hay Analysis Guide from UW Extension.
  2. Consider reducing livestock numbers by culling in order to match forage supply with livestock needs. This option should be considered after a review of feed costs as well as cull prices. For more information see Extension's page on Drought management for Minnesota cow-calf producers.
  3. severely drought stressed pasture
    Severely drought stressed pasture. Photo
    credit: Mercedes Moffett
    Seed cool season grasses such as spring oats and annual ryegrass into dormant pastures or into cropland to provide supplemental forage into the late fall. Success of seeding cool season grasses is best before early September and is dependent on the resumption of adequate rainfall. Options and timing for planting are provided on Extension's Emergency Forages Table page.
  4. Use herbicides to control perennial weeds like thistle that emerge when pasture grasses go dormant. It is best to control weeds during wetter periods when they are actively growing. This results in improved translocation of systematic herbicides and killing of crowns, lateral roots, and rhizomes. Always read the herbicide label prior to use. Ensure the product is labeled for pastures and follow all grazing restrictions and recommendations related to environmental conditions at the time of use.
  5. Fertilize pastures. Fertilizer use will be most efficient if it is applied before early September and its value is dependent on the resumption of adequate rainfall. Nitrogen fertilizer (about 50 lb/acre) is frequently used to improve productivity of grass pastures but P, K, and S fertilizers are beneficial when warranted by soil tests.
  6. Pasture planning for 2024. Review your overall pasture management plan and goals. Assess the return from increasing inputs, use of rotational grazing, and planting some emergency pastures to use when next summer’s drought occurs.

Additional readings about specific forages in the drought:


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