The Turf Doc: Burning down the turf

Karl Danneberger

A few years ago, I received an email from a golf course that had been covered — like snow — in a thick layer of volcanic ash. The course was located in the Patagonia region of Argentina, and the volcanic ash had drifted from erupting volcanic mountains in Chile. The questions asked of me were: What would the ash do to the turf? And, what should we do about it?

My first thought was, how did they get my name? We don’t have volcanoes in Ohio … at least not at the moment. Not able to give an intelligent answer, I contacted a former student and colleague at the University of Chile for help. My colleague, Alejandra Acuña, Ph.D., identified a forage specialist in her department whose research focus was on the impact of volcanic ash on forage production. Who would believe that extension fact sheets on the impact of volcanic ash on pastures existed? Needless to say, the golf course was very appreciative of this forage researcher’s help and reassurances.

As I have watched and read about the horrific fires that have ripped through and engulfed much of the western United States, leaving a burned and bare landscape like a volcanic eruption, I’ve wondered about the impact fires have on turfgrasses. Except for seed production, fire or burning is not widely discussed or written about in our profession. Yet, fire has had a prominent role in grassland management in the past and to a lesser degree now.

West of the Mississippi River, prescribed burns (i.e., controlled fires or planned fires) are still used by land managers and farmers. In some cases where allowed, homeowners will burn their lawn. In most cases, notifying the local fire department is advisable.

Vegetation burning returns nutrients to the soil and helps new plants germinate by breaking the thick outer seed coat. The secondary impact of fires includes controlling brush and weeds and helping reduce ticks, mice and parasite populations. Fire is part of the rejuvenation of past prairies through the Great Plains.

The fact is we do not live in the 1800s. Driving down a county road while a ditch or large pasture is burning or along a highway in the northwestern United States, like the Willamette Valley in Oregon, quickly brings into focus the downside to burning. The physical presence of smoke can cause serious visibility and air quality concerns. Field burning like in the Willamette Valley requires strict environmental and weather restrictions, including how much area can be burned. A significant human population and wildfires do not mix.

Ecologically, fire impacts grass diversity and species composition. I’ve listed below the ecology impacts I find interesting and applicable, much of which is based on research and observation of tall and short grass prairies.

Grasses recover back to their original state before the fire more quickly than shrubs and trees.

• Frequent fires favor grasses over trees.
• Grasses are more tolerant of fire when dormant.
• Less nitrogen is lost when a dormant turf is burned.
• Researchers at Curtis Prairie at the University of Wisconsin report that tall grass prairie could tolerate a burn every year. They found that the health of the prairie was the highest when it burned every three to five years.
• Cool-season turfgrasses are favored over warm-season turfgrasses by late summer or early fall for burning because cool-season grasses are not as actively growing compared to warm-season turfgrasses.
• Conversely, spring burning favors warm-season turfgrasses over cool-season turfgrasses because they are dormant or not actively growing.
• Rhizomatous turfgrasses are less damaged from fire compared to stoloniferous turfgrasses. Underground rhizomes allow quicker sprouting of new plants. The deeper the rhizome, the more protected the plant.
• Drought increases the severity of fire effects.

The continual occurrence and increased severity of the western fires are dramatically shown every night on the news. A sobering thought is what are these vast areas going to look like in the future?