Controlled burn at Grimes Farm helps preserve prairie grasses

T-R PHOTO BY GARRY BRANDENBURG - A controlled burn of prairie grasses was held Monday evening at the Grimes Farm. Over 100 spectators watched as staff of the County Conservation Board placed a backfire line into the wind. Then when that buffer was wide enough, a large segment of reconstructed prairie grasses was allowed to burn with the wind. Spectacular high flames carried by the wind did not disappoint the viewers. Fire is a management tool that helps remove thatch materials. When the exposed land warms with new sunshine and rainfall, new green prairie grass and prairie flower growth points will sprout with new vigor. This week, if weather allows, additional controlled burns will be conducted at other prairie sites in Marshall County.

Earlier this week, six acres of prairie grass at Grimes Farm blazed with fire at its annual, public controlled burn.

The purpose of the burn is to manage and maintain the prairie area by killing any sapling trees that are encroaching on the land, said Marshall County Conservation Board President Mike Stegmann.

He said only half of the 12-acre prairie land in that area was burned to minimize the impact on other forms of wildlife.

“There are insects that either lay their eggs there or caterpillars within chrysalises in the stocks of some of the plants, so we don’t want to kill all the insects that live in the prairie,” he said. “There are some ground nesting birds in the area too.”

Stegmann said fire is the most efficient way to achieve results. He noted that ash from the flames releases nutrients back into the soil at a much faster rate than what occurs during natural decomposition.

“We start our burn process in the summer before the burn,” he said. “We’ll mow a burn break, which means we’re mowing an area around the fields we want to burn next year, and we’ll keep that vegetation down very low, and what happens is that allows the grass to green up sooner in those areas and it prevents the fire from crawling across,” Stegmann said.

A controlled prairie burn starts in the downwind side of the field, and the area is ringed in fire, using a drip torch, with a mixture of diesel fuel and gasoline.

“We light the tip of it and it drops fuel right along the edge of our burn break, and we slowly go along there, and as it burns back into the wind, that provides an additional buffer that the fire will remain contained and controlled,” Stegmann said. “Anything that starts to creep out on the edges where we light it, we immediately put out with water.”

The burned area rebounds quickly. As perennial plants, the organic matter will soon decompose. Stegmann said the plants underground are alive and healthy, possessing roots as deep as 20 feet in some places.

“As soon as we get another warm rain it will green right back up,” he said.

MCCB staff conduct controlled burns throughout the year at the other county sites in which it manages. However, those are not open for public viewing.

“Some of the burns we do, such as at the Marietta Sand Prairie, will be upwards of 50 acres,” he said.

Stegmann said if private land owners are interested in doing controlled burns of prairie grasses, pre-planning is key. The Iowa DNR Wildlife Bureau maintains a Private Lands Program, which can offer some tips.

“Start planning now for next year, because you can divide up your field with mowing these burn breaks. If you didn’t prepare last year for this calendar year, don’t burn,” Stegmann said.

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Contact Sara Jordan-Heintz at 641-753-6611 or sjordan@timesrepublican.com