Scientists Outline Burning Strategies For Tallgrass Prairie
March 15, 2006

Less than 4% of the original tallgrass prairie remains intact, and an overwhelming majority of it is located in the Flint Hills of Kansas. To protect it and keep it in its natural state, Kansas State University (K-State) scientists and other prairie ecologists say it’s important to conduct routine prescribed burns.

Fire has always been a key ecological process in the tallgrass prairie. In pre-European settlement times, the prairie burned in a variable, but frequent regime (two to five fires per decade), said Walt Fick, range management specialist with K-State Research and Extension. Periodic fire is essential to the preservation and sustainability of these grasslands.

The prairie cannot continue to exist without fire, Fick said. Frequent fire increases the growth and abundance of native prairie grasses and prevents the establishment and spread of invasive woody plants.

The prescribed (planned) burning of prairie is a combustion process and, like all such processes, grassland burning releases particulates, oxides of nitrogen, carbon and other substances into the air. The reduction in air quality is an environmental downside of extensive burning, but these effects are transient and not chronic.

The temporary reduction in air quality has drawn the attention of both the Environmental Protection Agency (EPA) and the Kansas Department of Health and Environment (KDHE). Both agencies became concerned in April 2003, when the air quality in Kansas City did not meet acceptable standards. Because of weather conditions in 2003, much of the Flint Hills burned during a three-day time span in mid-April, resulting in smoke that hung in the atmosphere and drifted on air currents into Kansas City, Kan., and Kansas City, Mo. The smoke caused a spike in air particulate matter. Each spring since 2003, when pastures are being burned, a significant increase in air particulate matter has been detected in the Kansas City area, Fick said.

Knowing the environmental value of tallgrass prairie burning, EPA and KDHE officials sought the advice of K-State Research and Extension, the Natural Resources Conservation Service (NRCS) and the Kansas Department of Agriculture. A committee was formed to study and recommend ways to manage smoke emission from burning.

Committee members acknowledged that dry conditions across the state have left many areas under a burn ban, but the members are making the following recommendations to landowners who are considering burning tallgrass prairie if sufficient rain is received prior to April burning times. The recommendations should minimize the amount of smoke particulate matter drifting into major metropolitan areas.

• Wind speed: Wind speeds of 5 to 15 miles per hour (mph) are best. As winds reach 20 mph, the chances of controlling a fire in a good pasture fuel-load are slim.

• Lack of wind speed: No wind means that a breeze will come up in a few minutes, but you don’t know from which direction. A 5-mph breeze is more dependable.

• Relative humidity: Plays a big part in conducting a good controlled burn. Relative humidity of 40% to 70% is acceptable. Below 40% puts the area into a high fire danger situation, and controlling fires can be difficult. Above 70% slows the burn because it hampers getting the fire to carry through the fuel, and smoke may be increased.

• Air temperature: Should be 55° F to 80°. The cloud cover should be less than 70% for safe burning. Clouds will trap smoke, and a minimum ceiling of 2,000 feet (ft.) is required. Both conditions are necessary to get rid of the smoke. Pick a day when the smoke goes up high, indicating a good ceiling, is important.

“Burning is a necessary practice of grassland management, but it’s important that landowners take the time to prepare, have the right equipment, enough help, and pick the right weather conditions to conduct the burn,” said Mike Holder, K-State Research and Extension agent in Chase County and a member of the committee. “Counties vary on what they require for controlled burning. Some require a permit, others just give permission the day of the burn.”

Holder advises those who are considering a controlled burn to check with their local sheriff dispatcher to find the requirements for the county in which they plan to conduct a burn.

The proper time to burn tallgrass prairie has been debated by experts. But, 40 years of research by K-State indicates that burning in mid-April (early April in southern Kansas and late April in northern Kansas) will result in the best gains in stocker cattle. These increased gains are due to increased forage quality and/or increased forage intake of cattle grazing burned areas.

Jeff Davidson, K-State Research and Extension agent in Greenwood County, noted, “Cow-calf producers don’t get the gain advantage that stocker producers do from burning. However, they should still burn every two to three years to keep woody plants from encroaching on the prairie. The timing of burns for cow-calf producers is not as crucial as it is for stocker producers.”

Land enrolled in the U.S. Department of Agriculture (USDA) Conservation Reserve Program (CRP) may need to be burned at least every two to three years to prevent woody plant encroachment. The program allows prescribed burning to occur on CRP acres between the dates of Feb. 1 and April 15. However, CRP contract managers need to check with local USDA Farm Service Agency (FSA) and NRCS officials for specific guidance.

“Several things should be considered before lighting that match,” Davidson said. “Not all burns are the same. Timing is important, but the weather conditions the day of the burn can affect the degree of brush control obtained, completeness of the burn and smoke particles emitted.”

A K-State publication, titled “Prescribed Burning as a Management Practice,” offers details of burning. More information about prescribed burning is available at Extension offices or on the K-State Extension Web site at www.oznet.ksu.edu/library/crpsl2/l815.pdf.

— Release written by Mary Lou Peter-Blecha of K-State Research & Extension, which provided the article.