A Texas Cooperative Extension range expert in Uvalde says landowners should exercise caution when grazing livestock on recently burned pastures. Robert Lyons says 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," Lyons says. "Livestock benefit nutritionally from the tender green re-growth that fire provides. But if post-burn grazing isn't done correctly, the grass will suffer and any short-term livestock nutritional benefits will be lost."
Grasses need enough green growth to produce food for a healthy root system, he says.
"Top growth supplies food for the roots to function and grow, and the roots absorb the water and nutrients needed by the aboveground growth to manufacture food," he says.
When overgrazing occurs, root growth stops and the root system shrinks. Small root systems make the plant unable to compete with neighboring weeds and brush for water and nutrients.
Lyons says fire makes new green plant material, preferred by grazing animals, available by removing old 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 continue to graze burned patches, eventually damaging the plants. Uniform burns across a whole pasture remove all old plant growth and levels 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 says. The new growth makes them more palatable, and higher in protein.
This improved forage quality can benefit livestock performance, but only lasts 3-6 months, Lyons says.
"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 adds. 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 says. No more than 50-60% of a grass plant's new top-growth should ever be removed.
"The bottom line is burned pastures will recover with enough rainfall, time and proper grazing management," he says. -- Steve Byrns, Southwest Farm Press, a BEEF magazine sister publication.