Lighting up the prairie

by Mark Parker

March 27, 2008 10:20 am

— The browns and yellows of last season’s native range growth will soon be blackened by a rejuvenating orange blaze.
Fire will help keep the prairie healthy, just as it has for centuries. From the Osage country of Oklahoma, up through the Flint Hills of Kansas, prescribed burns will put extra pounds of beef on stocker cattle, keep the woody-plant invaders at bay and provide better habitat for wildlife.
But it’s not as simple as lighting a feed sack and dragging it across the edge of the pasture—not if you’re going to do it right, anyway.
“The prescribed burning season is the most intense part of the year for us,” says Hamilton, Kan., cattleman Mike Collinge. “It’s a very important practice and there’s a lot to do in a short period of time. There’s no way to get all of the conditions and situations to line up perfectly so you have to analyze a lot of factors and make a decision on whether or not to light that fire. That can be pretty stressful because you really need to burn, from an economic standpoint and for the benefit of the range, but you want to do it right and you want to do it responsibly.”
At the outset, the range manager has to decide what he or she wants to accomplish. Lighting up the range early in the burn season will generally benefit the forbes—and in turn, wildlife—in the prairie ecosystem while pushing the far end of the season will do a better job of controlling woody species such as buckbrush.
And somewhere in the middle is the time that best stimulates big bluestem growth and the resulting beef gains the native grass is famous for.
“You can’t use a very broad brush to paint prescribed burning recommendations,” says NRCS Rangeland Management Specialist David Kraft, “but it’s clear that fire is a powerful tool in stimulating positive vegetative growth of native warm season species and in controlling many invasive plants that compete for space, sunlight and moisture.”
This spring, there’s a pretty good fuel load for range managers to work with. That, according to Kraft, will open the burning window a little wider. If pastures were grazed down, there would be more green matter from cool season plants and annuals like sedges, resulting in much less desirable burn conditions. Some managers will graze a brushy pasture lightly the previous season to ensure that there is adequate fuel for a good, hot burn the next spring.
This year, however, it looks like there will be plenty of fuel throughout native grass country.
“Good moisture last summer gave us good recovery in the Flint Hills and there’s generally more dry matter than usual to help carry and spread a prescribed burn,” Kraft says. “A quicker fire causes less damage to the grasses and, because the heat rises up and away from the surface, it does more damage to the woody plants you want to control.
“Because we have a good fuel load, grass managers who need to control brush may be able to burn a little later. On native rangeland, it’s hard to burn too late in terms of hurting the plant community. You may postpone grazing just a little but animal performance will make up for it.”
Kansas State University research indicates that early burns result in lower forage yields while there is no difference in production between late-burned and non-burned rangeland.
In general, Kansas burn date recommendations for grazing purposes run through the month of April with prescribed burns down on the Oklahoma-Kansas line starting earliest and those up around Manhattan, Kan., getting lit toward the end of the month.
Right in the heart of the Flint Hills, Greenwood County K-State Ag Agent Jeff Davidson has a general recommendation of April 15 for the cattlemen in his county. That’s a trigger point designed to maximize stocker cattle performance and help control woody plant species.
Davidson knows, however, that a grass manager facing fickle weather conditions and a lot of acres to burn will have to spread that task out over a wider period.
“If you have a pasture along the south side of a highway, for example, you’re going to have to catch a north wind because of the potential for smoke blowing across the road plus you have to have all the other conditions that make it safe to burn,” he points out. “If you catch a day early in the month that fits, you’re probably going to take advantage of it.”
And that’s okay with Davidson and Kraft. Because burning pastures has become somewhat controversial in some corners, spreading the burn season out is probably a good idea.
A few years ago, an atmospheric inversion during the burn season resulted in air quality thresholds to be exceeded in the Kansas City area and events such as that add pressure for range managers to consider environmental conditions before lighting up a pasture.
From the cattleman’s standpoint, though, burning native range is a no-brainer. Years of Kansas State University research shows enhanced stocker cattle gains resulting directly from properly-timed burns.
That could be more important this year than ever before. Virtually all beef production inputs, from feed to fuel, are up pretty significantly. That means graziers need to really make the most of their forage. Whether they take the cattle on to the feedlot themselves or sell them, they know that their best bet is to maximize grass gains and minimize days in the feedlot.
Safety, of course, is another critical factor for prescribed burns and Davidson offers these considerations:
•Wind speed: Wind speeds of 5 to 15 miles per hour 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 is required. Both conditions are necessary to get rid of the smoke. Picking a day when the smoke goes up high, indicating a good ceiling, is important.
•Remember to call the local sheriff dispatch and let them know you are planning to burn. It prevents unnecessary “runs” by the rural fire department.
Busier highways, more houses scattered across the countryside, environmental concerns—all of it adds up to an extremely complex situation for range managers but the benefits of a prescribed burn are as clear as ever.
“We try to look at the whole picture,” Mike Collinge explains. “There’s no doubt that burning helps with cattle gains and no question about its brush control impact. And, we’re interested in helping wildlife habitat, too. The good news is that a lot of these things tie together and a well-managed burn can have many benefits.”

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