UT Institute of Agriculture Offers Tips for Prescribed Burns

Prescribed burn in Tennessee

Prescribed burns can suppress weeds and help native grasses grow more quickly.

Looking for a way to build up your native grass pastures? Burn them down, first.

Prescribed burning is a widely used and effective tool for managing pastures and fields of native grasses. Carefully managed burns can help native grasses grow more quickly, remain healthy and reduce weeds.

To make the best use of prescribed burns to suppress weeds, landowners need to consider both the types of weed that need to be suppressed to time the burn.

Dr. Pat Keyser, professor and director of the Center for Native Grasslands Management at the University of Tennessee Institute of Agriculture, has some helpful tips for deciding when, where and how to burn. "Earlier burns—those in March through early April—can be very effective at reducing encroaching cool-season weeds. That is because those weeds are often actively growing at this time and the fire either kills them outright, in the case of annuals or seedlings of perennials, or suppresses them in the case of established perennials." Keyser advises landowners not to burn too early in the spring, however. By burning in early March, for instance, tall fescue (a cool-season perennial) will be ready to start growing, but the natives are still weeks away from breaking dormancy, he said.

Planning a burn for later in the spring (mid-April into May) comes with its own set of pros and cons. Keyser warns that burning during this period may actually set back the growth of native grasses because they are actively growing at this point. "However, these later fires, as well as those that occur toward the end of the growing season, can suppress woody species such as sweetgum seedlings or briars." Keyser points out. "If these woody stems are still small, they may be killed outright by these growing-season fires."

Early April is another good candidate for a potential burn. Keyser suggests that burning during this period could lead to the native grasses growing more rapidly than normal. The post-burn soil will be blackened and enriched with nitrogen and phosphorous, which can speed up the growth of the native grasses. The major downside to this method, Keyser suggests, is that the benefit is rather short-lived.

Regardless of when you decide to burn, the native grasses that grow following the prescribed burn will provide higher quality forage for your grazing animals. "In fact," says Keyser, "studies have shown that cattle and bison selectively graze portions of pastures that have been burned within the same growing season."

It is important to note that prescribed burns are not necessary for managing native grasses. Keyser suggests that native grasses can thrive for years without the use of prescribed burns. Furthermore, he recommends burning only once every two or three years, if you decide to burn at all. Burns can also be very dangerous and should not be attempted without help from someone experienced with prescribed burns. “Variations in fuel load and weather patterns can affect the behavior of a prescribed burn,” adds Tim Phelps,” with the Tennessee Department of Agriculture Division of Forestry. “As such, it is very important to follow safe burning practices to maximize safety precautions and minimize the risk of the fire escaping,” Phelps said.

Before planning to burn any open spaces in Tennessee, landowners should consult with the Tennessee Department of Agriculture Division of Forestry. A burning permit may be required. See the website
BurnSafeTN.org for more information.

For more information on effective field management, please visit the UT Beef and Forage Center website at
utbfc.utk.edu. From there, you can explore the "Forages" tab at the top of the screen for additional resources.

You may also contact your local county UT Extension Office.

The UT Institute of Agriculture provides instruction, research and outreach through the UT College of Agricultural Sciences and Natural Resources, the UT College of Veterinary Medicine, UT AgResearch, including its system of 10 research and education centers, and UT Extension offices in every county in the state.



Dr. Pat Keyser, professor and Director, UTIA Center for Native Grasslands Management, 865-974-0644, pkeyser@utk.edu