A Texas Cooperative Extension range expert in Uvalde said landowners should exercise caution when grazing livestock on recently burned pastures.
Robert Lyons, Extension range specialist, said proper management is a must to prevent serious grass damage after a fire.
"As with any fire, prescribed or wild, ensuring grass survival is a primary management goal," said Lyons. "Livestock benefit nutritionally from the tender green forage re-growth fire provides. But if post-burn grazing is not done correctly, the grass will suffer and any short-term livestock nutritional benefits will be lost."
Lyons said grasses need enough green growth to produce food for a healthy root system.
"Top growth supplies food for the roots to function and grow, and the roots absorb the water and nutrients needed by the above-ground growth to manufacture food," he said. "When overgrazing occurs, root growth stops. When root growth stops, the root system shrinks. Small root systems weaken the plant and make it unable to compete with neighboring weeds and brush for water and nutrients."
Lyons said fire makes new green plant material available by removing old growth. Grazing animals prefer this new growth. If a fire doesn't remove the old, coarse growth from an entire pasture, livestock will concentrate on the burned patches and avoid the unburned areas.
He said animals will keep grazing these burned patches and eventually damage the plants. Uniform burns across a whole pasture remove all old plant growth and level the playing field, allowing new growth from all the grasses.
Less desirable grasses and unpalatable old-growth plants are more likely to be grazed after burning, he said. The new growth makes them more palatable, and higher in protein.
"This improved forage quality can benefit livestock performance, but it only lasts three to six months," Lyons said. "Young cattle, thin animals, and those in early lactation benefit most from the improved nutritional quality following a fire. Naturally, post-burn grazing depends on adequate rainfall to stimulate grass re-growth."
Grazing needs to be deferred until plants have vigorous re-growth, he added. Livestock need quality forage, but they also need adequate quantities to meet their nutritional requirements. In addition, grazing should be gauged according to available re-growth, Lyons said. No more than 50 percent to 60 percent of a grass plant's new top-growth should ever be removed.
"The bottom line, though, is that burned pastures will recover with enough rainfall, time and proper grazing management," he said.