It seems counter-intuitive: burning a field to encourage new growth. It’s a practice, though, that has been used for thousands of years to feed the soil with nutrition-rich ashes. The tallgrass prairie on the south and west sides of the Hygienic Laboratory has new life because of a burn conducted on April 2 by the University of Iowa Facilities Maintenance Landscape Services section.

UI Facilities Maintenance staff begin a controlled burn of the tallgrass prairie on the south side of the State Hygienic Laboratory.

The prairie was planted as part of the building’s LEED (Leadership in Energy and Environmental Design) certification process. Creating a prairie provides both water-efficient landscaping and habitat restoration, part of LEED criteria.

Tallgrass prairies once covered more than 40 percent of the United States; Iowa was the only state entirely within that ecosystem. But, the introduction of the steel plow changed the prairie into farmland. Now only about a tenth of a percent of the original prairie still exists in the state.

As Iowa’s environmental and public health laboratory, preserving this endangered ecosystem is part the Hygienic Laboratory vision of sustaining Iowa’s quality of life.

David Larabee-Zierath, environment laboratory specialist and self-described prairie enthusiast, explained that, “the prairie ecosystem, unique to the North American Midwest, evolved under fire. The plants native to the prairie survive, and even thrive, under burn conditions.” Non-prairie species, thatch and undesirable woody vegetation are destroyed.

Most of the early prairie burns were started by lightning. As Native Americans learned that new growth from burned land attracted bison, they began using fire to create better prairie areas.

The burn on the grounds of the Hygienic Laboratory was started in the early afternoon when winds wouldn’t create a danger to the surrounding buildings. A certain amount of wind is needed to feed oxygen to the fire and direct the flames, according to Larabee-Zierath. But too much wind could allow the fire to get out of control. It didn’t.

Water was sprayed around the edge of the prairie to create a four-foot barrier between the burning land and the surrounding fields and buildings.

To fuel the burn, a mixture of gasoline and kerosene was applied with specially designed torches. The mixture dripped to the ground to start the fire. The gasoline in the mixture kept the liquid burning long enough to reach the ground and the kerosene kept the fire going.

Armed with these torches, the UI team lit the prairie on the downwind side and then moved ahead of the fire’s edge to light new fire lines. As the lines burned together, the fire contained itself. After the downwind side was burned, the windward side was torched.

In less than an hour, the job was done. The tallgrass had been burned away, leaving a large swath of charred ground bordering the Hygienic Laboratory.

A week later, new plants sprouted among the ashes and a new cycle of life began for the tallgrass prairie.