Summer Heat, Dryness Take Toll on Warm- and Cool-Season Grasses

Summer Heat, Dryness Take Toll on Warm- and Cool-Season Grasses

UNL specialist examines the impact on grass and also offers some drylot feeding options.

Summer heat hit Nebraska grass and forages hard this spring and summer. How do high temperatures affect different types of forage plants?

Bruce Anderson, University of Nebraska-Lincoln forage specialist, says alfalfa and clovers, bromegrass, orchardgrass, fescues, and wheatgrasses are all hurt during hot weather. The impact is very slow growth, lower forage quality as the plants burn up the good nutrients. It also affects root reserves after defoliaton. These conditions are worse if it also dry.

Summer Heat and Dryness Take Toll on Warm- and Cool-Season Grasses

Warm-season grasses are just the opposite, according to Anderson.  Millet, sudangrass, sorghums, and native bluestems, gramas, switchgrass, and other warm-season grasses thrive when the temperature is around 90 degrees. Their metabolism runs at peak efficiency when it is hot so they grow rapidly while maintaining reasonable forage quality and good root growth.

"But that's only if these plants have adequate moisture," Anderson says. "Once they dry up, these grasses will overheat too, just like cool-season grasses do at lower temperatures.

As you graze or hay, be aware of the stress weather is putting on your forage. When it's too hot, be prepared to allow plants to recover for a longer time before next use. And don't expect high feed values when the "goodies" are burned right out of the plants.

Proper expectations and management adjustments can limit the stress from stressful weather, he says.

Feeding on pasture is one option to care for cattle when pasture grass is gone, according to Anderson. However, be sure that you don't harm your pasture when feeding the animals.

Drought has made many pastures almost useless as cattle feed. If you keep your cows you need to feed them hay or other supplements. And the most convenient place to feed them often is the pasture.

"But as long as animals are on the pasture, they will continue to do some damage," Anderson says. "They will nibble at what little grass remains and they will trample and cut up plant crowns with their hooves. Even lying on plants while resting will cause some damage. And any damage caused by feeding will lengthen the amount of time it will take your pasture to recover before it is in condition to be grazed again."

To minimize the total damage done to your pastures while feeding, use one of two feeding methods. The first is called a sacrifice paddock and is similar to converting a small portion of your pasture into a temporary feedlot. Do all your feeding in one small area, protecting the rest of your pasture but potentially killing all plants currently there.  If you choose this sacrifice paddock method, be sure the site won't erode after grass is gone and select a site that may be reseeded easily since you very well may need to do so later on, he adds.

The second option is the moving feed bunk method. Pasture damage is relatively small when animals are concentrated on an area for just a couple days. The moving feed bunk method involves moving feeding sites throughout your pastures every couple of days. It's a difficult method to use if you actually are using feed bunks, but if all your hay or feed goes on the ground it isn't hard to accomplish.
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